Sync source code from Tizen:BaseHEAD2.0_alphamaster2.0alpha1.0_post

15 files changed, 15572 insertions, 0 deletions

diff --git a/stl/dbstl_base_iterator.h b/stl/dbstl_base_iterator.h
new file mode 100644
index 0000000..577ce65
--- /dev/null
+++ b/stl/dbstl_base_iterator.h
@@ -0,0 +1,498 @@
+/*-
+ * See the file LICENSE for redistribution information.
+ *
+ * Copyright (c) 2009 Oracle.  All rights reserved.
+ *
+ * $Id$
+ */
+
+#ifndef _DB_STL_DB_BASE_ITERATOR_H
+#define _DB_STL_DB_BASE_ITERATOR_H
+
+#include "dbstl_common.h"
+
+START_NS(dbstl)
+
+template <Typename ddt>
+class ElementRef;
+template <Typename ddt>
+class ElementHolder;
+
+/** \defgroup dbstl_iterators dbstl iterator classes
+Common information for all dbstl iterators:
+
+1. Each instance of a dbstl iterator uniquely owns a Berkeley DB cursor,
+so that the key/data pair it currently sits on is always valid before it moves
+elsewhere. It also caches the current key/data pair values in order for member
+functions like operator* /operator-> to work properly, but caching is not 
+compatible with standard C++ Stl behavior --- the C++ standard requires the 
+iterator refer to a shared piece of memory where the data is stored, 
+thus two iterators of the same container sitting on the same element should 
+point to the same memory location, which is false for dbstl iterators. 
+
+2. There are some functions common to each child class of this class which have
+identical behaviors, so we will document them here.
+
+@{
+This class is the base class for all dbstl iterators, there is no much to say
+about this class itself, and users are not supposed to directly use this class
+at all. So we will talk about some common functions of dbstl iterators in 
+this section.
+
+\sa db_vector_base_iterator db_vector_iterator db_map_base_iterator 
+db_map_iterator db_set_base_iterator db_set_iterator
+*/
+template <Typename ddt>
+class db_base_iterator
+{
+protected:
+	typedef db_base_iterator<ddt> self;
+	friend class ElementHolder<ddt>;
+	friend class ElementRef<ddt>;
+
+	// The container from which this iterator is created.
+	mutable db_container *owner_;
+
+	bool dead_; // Internally used to prevent recursive destruction calls.
+
+	// Whether or not to always get current key/data pair directly from db;
+	// If true, always poll db, slower but safe for concurrent use;
+	// otherwise faster, but when multiple iterators point to the same
+	// key/data pair (they definitely have same locker id) and use some
+	// iterators to update current key/data pair, then other iterators'
+	// key/data pairs are obsolete, need to call iterator::refresh().
+	//
+	bool directdb_get_;
+
+	// Whether to do bulk retrieval for a read only iterator. If non-zero,
+	// do bulk retrieval and use this member as the bulk buffer size,
+	// otherwise, do not use bulk retrieval. While doing bulk retrieval,
+	// no longer read from database even if directdb_get is true.
+	u_int32_t bulk_retrieval_;
+
+	// Whether to use DB_RMW flag in Dbc::get. Users can set this flag in
+	// db_container::begin(). The flag may be ignored when there is no
+	// locking subsystem initialized.
+	bool rmw_csr_;
+
+	// Whether this iterator is a db_set/db_multiset iterator.
+	bool is_set_;
+
+	// Whether this iterator is read only. Default value is false.
+	// The const version of begin(), or passing an explicit "readonly"
+	// parameter to non-const begin() will will create a read only
+	// iterator;
+	//
+	bool read_only_;
+
+	// Iteration status. If in valid range, it is 0, otherwise it is
+	// INVALID_ITERATOR_POSITION.
+	mutable int itr_status_;
+
+	// Distinguish the invalid iterator of end() and rend(). If an
+	// iterator was invalidated in operator++, inval_pos_type_ is
+	// IPT_AFTER_LAST, else if in operator-- it is IPT_BEFORE_FIRST.
+	// For random iterator, inval_pos_type_ is also updated in random
+	// movement functions. This member is only valid when itr_status_ is
+	// set to INVALID_ITERATOR_POSITION.
+	mutable char inval_pos_type_;
+	// Values to denote the invalid positions.
+	const static char IPT_BEFORE_FIRST = -1;
+	const static char IPT_AFTER_LAST = 1;
+	const static char IPT_UNSET = 0;
+
+	virtual void delete_me() const { delete this;}
+
+	virtual db_base_iterator* dup_itr() const
+	{
+		THROW(InvalidFunctionCall, (
+		    "\ndb_base_iterator<>::dup_itr can't be called.\n"));
+		
+	}
+
+	inline bool is_set_iterator() const
+	{
+		return is_set_;
+	}
+
+	// The following two functions can't be abstract virtual for
+	// compiler errors.
+	virtual int replace_current(const ddt&)
+	{
+		THROW(InvalidFunctionCall, (
+		    "\ndb_base_iterator<>::replace_current can't be called\n"));
+	}
+
+	virtual int replace_current_key(const ddt&)
+	{
+		THROW(InvalidFunctionCall, (
+	    "\ndb_base_iterator<>::replace_current_key can't be called\n"));
+	}
+
+public:
+#if NEVER_DEFINE_THIS_MACRO_IT_IS_FOR_DOXYGEN_ONLY
+	/// Read data from underlying database via its cursor, and update 
+	/// its cached value.
+	/// \param from_db Whether retrieve data from database rather than
+	/// using the cached data in this iterator.
+	/// \return 0 if succeeded. Otherwise an DbstlException exception 
+	/// will be thrown.
+	int refresh(bool from_db = true);
+
+	/** Close its cursor. If you are sure the iterator is no longer
+	used, call this function so that its underlying cursor is closed
+	before this iterator is destructed, potentially increase performance
+	and concurrency. Note that the cursor is definitely
+	closed at iterator destruction if you don't close it explicitly.
+	*/
+	void close_cursor()  const;
+
+	/** Call this function to modify bulk buffer size. Bulk retrieval is
+	enabled when creating an iterator, so users later can only modify
+	the bulk buffer size to another value, but can't enable/disable
+	bulk read while an iterator is already alive.
+	\param sz The new buffer size in bytes.
+	\return true if succeeded, false otherwise.
+	*/
+	bool set_bulk_buffer(u_int32_t sz);
+	
+	/// Return current bulk buffer size. Returns 0 if bulk retrieval is
+	/// not enabled.
+	u_int32_t get_bulk_bufsize();
+#endif // NEVER_DEFINE_THIS_MACRO_IT_IS_FOR_DOXYGEN_ONLY
+
+	////////////////////////////////////////////////////////////////////
+	//
+	// Begin public constructors and destructor.
+	//
+	/// Default constructor.
+	db_base_iterator()
+	{
+		owner_ = NULL;
+		directdb_get_ = true;
+		dead_ = false;
+		itr_status_ = INVALID_ITERATOR_POSITION;
+		read_only_ = false;
+		is_set_ = false;
+		bulk_retrieval_ = 0;
+		rmw_csr_ = false;
+		inval_pos_type_ = IPT_UNSET;
+	}
+
+	/// Constructor.
+	db_base_iterator(db_container *powner, bool directdbget,
+	    bool b_read_only, u_int32_t bulk, bool rmw)
+	{
+		owner_ = powner;
+		directdb_get_ = directdbget;
+		dead_ = false;
+		itr_status_ = INVALID_ITERATOR_POSITION;
+		read_only_ = b_read_only;
+		is_set_ = false;
+		bulk_retrieval_ = bulk;
+		rmw_csr_ = rmw;
+		inval_pos_type_ = IPT_UNSET;
+	}
+
+	/// Copy constructor. Copy all members of this class.
+	db_base_iterator(const db_base_iterator &bi)
+	{
+		owner_ = bi.owner_;
+		directdb_get_ = bi.directdb_get_;
+		dead_ = false;
+		itr_status_ = bi.itr_status_;
+		read_only_ = bi.read_only_;
+		is_set_ = bi.is_set_;
+		bulk_retrieval_ = bi.bulk_retrieval_;
+		rmw_csr_ = bi.rmw_csr_;
+		inval_pos_type_ = bi.inval_pos_type_;
+	}
+
+	/**
+	Iterator assignment operator.
+	Iterator assignment will cause the underlying cursor of the right iterator
+	to be duplicated to the left iterator after its previous cursor is closed,
+	to make sure each iterator owns one unique cursor. The key/data cached 
+	in the right iterator is copied to the left iterator. Consequently, 
+	the left iterator points to the same key/data pair in the database 
+	as the the right value after the assignment, and have identical cached
+	key/data pair.
+	\param bi The other iterator to assign with.
+	\return The iterator bi's reference.
+	*/
+	inline const self& operator=(const self& bi)
+	{
+		ASSIGNMENT_PREDCOND(bi)
+		owner_ = bi.owner_;
+		directdb_get_ = bi.directdb_get_;
+		dead_ = false;
+		itr_status_ = bi.itr_status_;
+		read_only_ = bi.read_only_;
+		is_set_ = bi.is_set_;
+		bulk_retrieval_ = bi.bulk_retrieval_;
+		rmw_csr_ = bi.rmw_csr_;
+		inval_pos_type_ = bi.inval_pos_type_;
+		return bi;
+	}
+
+	/// Destructor.
+	virtual ~db_base_iterator() {}
+
+	////////////////////////////////////////////////////////////////////
+
+	/// \brief Get bulk buffer size.
+	///
+	/// Return bulk buffer size. If the size is 0, bulk retrieval is not
+	/// enabled.
+	u_int32_t get_bulk_retrieval() const { return bulk_retrieval_; }
+
+	/// \brief Get DB_RMW setting.
+	///
+	/// Return true if the iterator's cursor has DB_RMW flag set, false
+	/// otherwise. DB_RMW flag causes 
+	/// a write lock to be acquired when reading a key/data pair, so
+	/// that the transaction won't block later when writing back the 
+	/// updated value in a read-modify-write operation cycle.
+	bool is_rmw() const { return rmw_csr_; }
+
+	/// \brief Get direct database get setting.
+	///
+	/// Return true if every operation to retrieve the key/data pair the
+	/// iterator points to will read from database rather than using
+	/// the cached value, false otherwise.
+	bool is_directdb_get() const {return directdb_get_; }
+}; // db_base_iterator
+
+////////////////////////////////////////////////////////////////////////
+////////////////////////////////////////////////////////////////////////
+//
+// db_reverse_iterator class template definition.
+//
+// db_reverse_iterator is the reverse iterator adapter for all iterator
+// classes of dbstl. It makes an original iterator its reverse iterator.
+// We don't want to use std::reverse_iterator<> adapter because it is more
+// more expensive. Here we move the original iterator one position back to
+// avoid unnecessary movement.
+//
+/// This class is the reverse class adaptor for all dbstl iterator classes. 
+/// It inherits from real iterator classes like db_vector_iterator, 
+/// db_map_iterator or db_set_iterator. When you call container::rbegin(), 
+/// you will get an instance of this class.
+/// \sa db_vector_base_iterator db_vector_iterator db_map_base_iterator 
+/// db_map_iterator db_set_base_iterator db_set_iterator
+template <Typename iterator, Typename twin_itr_t>
+class _exported db_reverse_iterator : public iterator
+{
+public:
+	// typedefs are not inherited, so re-define them here.
+	//
+	typedef db_reverse_iterator<iterator, twin_itr_t> self;
+	typedef typename iterator::value_type T;
+	typedef iterator iterator_type;
+	typedef typename iterator::value_type value_type;
+	typedef typename iterator::reference reference;
+	typedef typename iterator::pointer pointer;
+	typedef typename iterator::iterator_category iterator_category;
+	typedef typename iterator::key_type key_type;
+	typedef typename iterator::data_type data_type;
+	typedef typename iterator::difference_type difference_type;
+	typedef typename iterator::value_type_wrap value_type_wrap;
+	// Construct a reverse iterator from iterator vi. We don't duplicate
+	// itrerator vi here because vi is not supposed to be used again.
+	// This function is supposed to be used by dbstl users, internally
+	// self::set_iterator method is used.
+	/// Constructor. Construct from an iterator of wrapped type.
+	db_reverse_iterator(const iterator& vi) : iterator(vi)
+	{
+		iterator::operator--();
+	}
+
+	/// Copy constructor.
+	db_reverse_iterator(const self& ritr)
+	    : iterator(ritr)
+	{
+	}
+
+	/// Copy constructor.
+	db_reverse_iterator(const 
+	    db_reverse_iterator<twin_itr_t, iterator>& ritr)
+	    : iterator(ritr)
+	{
+	}
+
+	/// Default constructor.
+	db_reverse_iterator() : iterator()
+	{
+	}
+
+	// Do not throw exceptions here because it is normal to iterate to
+	// "end()".
+	//
+	/// \name Reverse iterator movement functions
+	/// When we talk about reverse iterator movement, we think the 
+	/// container is a uni-directional range, represented by [begin, end),
+	/// and this is true no matter we are using iterators or reverse 
+	/// iterators. When an iterator is moved closer to "begin", we say it
+	/// is moved forward, otherwise we say it is moved backward.
+	//@{
+	/// Move this iterator forward by one element. 
+	/// \return The moved iterator at new position.
+	self& operator++()
+	{
+		iterator::operator--();
+		return *this;
+	}
+
+	/// Move this iterator forward by one element. 
+	/// \return The original iterator at old position.
+	self operator++(int)
+	{
+		// XXX!!! This conversion relies on this class or
+		// db_set_iterator<> having no data members at all, which
+		// is currently the case.
+		return (self)iterator::operator--(1);
+	}
+
+	/// Move this iterator backward by one element. 
+	/// \return The moved iterator at new position.
+	self& operator--()
+	{
+		iterator::operator++();
+		return *this;
+	}
+
+	/// Move this iterator backward by one element. 
+	/// \return The original iterator at old position.
+	self operator--(int)
+	{
+		// XXX!!! This conversion relies on this class or
+		// db_set_iterator<> having no data members at all, which
+		// is currently the case.
+		return (self)iterator::operator++(1);
+	}
+	//@} // Movement operators.
+
+	/// Assignment operator.
+	/// \param ri The iterator to assign with.
+	/// \return The iterator ri.
+	/// \sa db_base_iterator::operator=(const self&)
+	const self& operator=(const self& ri)
+	{
+		ASSIGNMENT_PREDCOND(ri)
+		iterator::operator=(ri);
+		return ri;
+	}
+
+	////////////// Methods below only applies to random iterators. /////
+	/// \name Operators for random reverse iterators
+	/// Return a new iterator by moving this iterator backward or forward
+	/// by n elements.
+	//@{
+	/// Iterator shuffle operator.
+	/// Return a new iterator by moving this iterator forward 
+	/// by n elements.
+	/// \param n The amount and direction of movement. If negative,
+	/// will move towards reverse direction.
+	/// \return A new iterator at new position.
+	self operator+(difference_type n) const
+	{
+		self ritr(*this);
+		ritr.iterator::operator-=(n);
+		return ritr;
+	}
+
+	/// Iterator shuffle operator.
+	/// Return a new iterator by moving this iterator backward 
+	/// by n elements.
+	/// \param n The amount and direction of movement. If negative,
+	/// will move towards reverse direction.
+	/// \return A new iterator at new position.
+	self operator-(difference_type n) const
+	{
+		self ritr(*this);
+		ritr.iterator::operator+=(n);
+		return ritr;
+	}
+	//@}
+	/// \name Operators for random reverse iterators
+	/// Move this iterator backward or forward by n elements and then 
+	/// return it.
+	//@{
+	/// Iterator shuffle operator.
+	/// Move this iterator forward by n elements and then 
+	/// return it.
+	/// \param n The amount and direction of movement. If negative,
+	/// will move towards reverse direction.
+	/// \return This iterator at new position.
+	const self& operator+=(difference_type n)
+	{
+		iterator::operator-=(n);
+		return *this;
+	}
+
+	/// Iterator shuffle operator.
+	/// Move this iterator backward by n elements and then 
+	/// return it.
+	/// \param n The amount and direction of movement. If negative,
+	/// will move towards reverse direction.
+	/// \return This iterator at new position.
+	const self& operator-=(difference_type n)
+	{
+		iterator::operator+=(n);
+		return *this;
+	}
+	//@}
+	/// \name Operators for random reverse iterators
+	/// Reverse iterator comparison against reverse iterator itr, the one
+	/// sitting on elements with less index is returned to be greater.
+	//@{
+	/// Less compare operator.
+	bool operator<(const self& itr) const
+	{
+		return (iterator::operator>(itr));
+	}
+
+	/// Greater compare operator.
+	bool operator>(const self& itr) const
+	{
+		return (iterator::operator<(itr));
+	}
+
+	/// Less equal compare operator.
+	bool operator<=(const self& itr) const
+	{
+		return (iterator::operator>=(itr));
+	}
+
+	/// Greater equal compare operator.
+	bool operator>=(const self& itr) const
+	{
+		return (iterator::operator<=(itr));
+	}
+	//@}
+	// Because v.rend() - v.rbegin() < 0, we should negate base version.
+	/// Return the negative value of the difference of indices of elements 
+	/// this iterator and itr are sitting on.
+	/// \return itr.index - this->index.
+	/// \param itr The other reverse iterator.
+	difference_type operator-(const self&itr) const
+	{
+		difference_type d = iterator::operator-(itr);
+		return -d;
+	}
+
+	/// Return the reference of the element which can be reached by moving
+	/// this reverse iterator by Off times backward. If Off is negative,
+	/// the movement will be forward.
+	inline value_type_wrap operator[](difference_type Off) const
+	{
+		self ritr(*this);
+		value_type_wrap res = ritr.iterator::operator[](-Off);
+		return res;
+	}
+
+}; // reverse_iterator
+//@} // dbstl_iterators
+END_NS
+
+#endif // !_DB_STL_DB_BASE_ITERATOR_H
diff --git a/stl/dbstl_common.in b/stl/dbstl_common.in
new file mode 100644
index 0000000..1712a48
--- /dev/null
+++ b/stl/dbstl_common.in
@@ -0,0 +1,453 @@
+#ifndef _DB_STL_COMMON_H
+#define _DB_STL_COMMON_H
+
+#ifdef DBSTL_DEBUG_LEAK
+#include "vld.h"
+#endif
+
+#include <assert.h>
+
+#include "db_cxx.h"
+
+// In release builds, the native assert will be disabled so we
+// can't use it in dbstl in cases where we rely on the expression being
+// evaluated to change the state of the application.
+//
+#if !defined(DEBUG) && !defined(_DEBUG)
+#undef dbstl_assert
+#define dbstl_assert(expression)
+#else
+#undef dbstl_assert
+#define dbstl_assert(expression) do {			\
+	if (!(expression)) {				\
+		FailedAssertionException ex(__FILE__, __LINE__, #expression);\
+		throw ex; } } while (0)
+#endif
+
+#ifndef SIZE_T_MAX
+// The max value for size_t variables, one fourth of 2 powers 32.
+#define SIZE_T_MAX 1073741824
+#endif
+
+#if defined( DB_WIN32) || defined(_WIN32)
+#include <windows.h>
+#include <tchar.h>
+#else
+#define TCHAR char
+#define _T(e) (e)
+#define _ftprintf fprintf
+#define _snprintf snprintf
+#define _tcschr strchr
+#define _tcscmp strcmp
+#define _tcscpy strcpy
+#define _tcslen strlen
+#define _tgetopt getopt
+#define _tmain main
+#define _tprintf printf
+#define _ttoi atoi
+#endif
+
+// Macro for HAVE_WSTRING (detected by configure)
+@WSTRING_decl@
+
+// Thread local storage modifier declaration.
+@TLS_decl@
+@TLS_defn@
+
+#if !defined(TLS_DECL_MODIFIER) && !defined(HAVE_PTHREAD_TLS)
+#error "No appropriate TLS modifier defined."
+#endif
+
+//////////////////////////////////////////////////////////////////////////
+/////////////////////////////////////////////////////////////////////////
+//
+// C++ compiler portability control macro definitions.
+// If a C++ compiler does not support the following capabilities, disabling
+// these flags will remove usage of the feature from DB STL.
+// Where possible a DB STL has implemented work-arounds for the missing
+// functionality.
+//
+#define HAVE_EXPLICIT_KEYWORD			1
+#define HAVE_NAMESPACE				1
+#define HAVE_TYPENAME				1
+
+// Platform specific compiler capability configuration.
+#ifdef WIN32
+#define CLS_SCOPE(clstmpl_name)
+#else
+
+// C++ standard: It is not possible to define a full specialized version of
+// a member function of a class template inside the class body. It needs to
+// be defined outside the class template, and must be defined in the namespace
+// scope.
+#define CLS_SCOPE(clstmpl_name) clstmpl_name::
+#define NO_IN_CLASS_FULL_SPECIALIZATION  1
+#define NO_MEMBER_FUNCTION_PARTIAL_SPECIALIZATION 1
+#endif
+
+#if HAVE_NAMESPACE
+#define START_NS(nsname) namespace nsname {
+#define END_NS }
+#else
+#define START_NS(nsname) struct nsname {
+#define END_NS };
+#endif
+
+#if HAVE_EXPLICIT_KEYWORD
+#define EXPLICIT explicit
+#else
+#define EXPLICIT
+#endif
+
+#if HAVE_TYPENAME
+#define Typename typename
+#else
+#define Typename class
+#endif
+
+//////////////////////////////////////////////////////////////////////////
+// End of compiler portability control macro definitions.
+////////////////////////////////////////////////////////////////////////
+
+//////////////////////////////////////////////////////////////////////////
+/////////////////////////////////////////////////////////////////////////
+//
+// Iterator status macro definitions.
+//
+#define INVALID_ITERATOR_POSITION -1 // Iterator goes out of valid range.
+#define INVALID_ITERATOR_CURSOR -2 // The iterator's dbc cursor is invalid.
+#define ITERATOR_DUP_ERROR -3 // Failed to duplicate a cursor.
+
+// Current cursor's key or data dbt has no data.
+#define INVALID_KEY_DATA -4
+#define EMPTY_DBT_DATA -5 // Current cursor's pointed data dbt has no data.
+#define ITERATOR_AT_END -6
+#define CURSOR_NOT_OPEN -7
+
+///////////////////////////////////////////////////////////////////////
+// End of iterator status macro definitions.
+//////////////////////////////////////////////////////////////////////
+
+//////////////////////////////////////////////////////////////////////
+//////////////////////////////////////////////////////////////////////
+//
+// Helper macros definitions.
+//
+// Use BDBOP and BDBOP2 to wrap Berkeley DB calls. The macros validate the 
+// return value. On failure, the wrappers clean up, and generate the
+// expected exception.
+//
+#define BDBOP(bdb_call, ret) do { 					\
+	if ((ret = (bdb_call)) != 0) throw_bdb_exception(#bdb_call, ret);\
+	} while(0)
+#define BDBOP2(bdb_call, ret, cleanup) do {				\
+	if ((ret = (bdb_call)) != 0) { (cleanup); 			\
+		throw_bdb_exception(#bdb_call, ret);}			\
+	} while (0)
+// Do not throw the exception if bdb_call returned a specified error number.
+#define BDBOP3(bdb_call, ret, exception, cleanup) do {			\
+	if (((ret = (bdb_call)) != 0) && (ret & exception) == 0) {	\
+		(cleanup); throw_bdb_exception(#bdb_call, ret);}	\
+	} while (0)
+
+#define THROW(exception_type, arg_list) do {		\
+	exception_type ex arg_list; throw ex; } while (0)
+
+#define THROW0(exception_type)	do {			\
+	exception_type ex; throw ex; } while (0)
+
+#define INVALID_INDEX ((index_type)-1)
+#define INVALID_DLEN ((u_int32_t)-1)
+
+#define DBSTL_MAX_DATA_BUF_LEN 1024 * 4096
+#define DBSTL_MAX_KEY_BUF_LEN 1024 * 4096
+#define DBSTL_MAX_MTX_ENV_MUTEX 4096 * 4
+#define DBSTL_BULK_BUF_SIZE 256 * 1024
+
+#define COMPARE_CHECK(obj) if (this == &obj) return true;
+#define ASSIGNMENT_PREDCOND(obj) if (this == &obj) return obj;
+//////////////////////////////////////////////////////////////////
+// End of helper macro definitions.
+//////////////////////////////////////////////////////////////////
+
+//////////////////////////////////////////////////////////////////
+//////////////////////////////////////////////////////////////////
+//
+// Public global function declarations.
+// These functions are open/public functionalities of dbstl for
+// dbstl users to call.
+//
+START_NS(dbstl)
+// _exported is a macro we employ from db_cxx.h of Berkeley DB C++
+// API. If we want to export the symbols it decorates on Windows,
+// we must define the macro "DB_CREATE_DLL", as is defined in dbstl
+// project property.
+/// \defgroup dbstl_global_functions dbstl global public functions
+//@{
+
+/// \name Functions to close database/environments.
+/// Normally you don't have to close any database 
+/// or environment handles, they will be closed automatically.
+/// Though you still have the following API to close them.
+//@{ 
+/// Close pdb regardless of reference count. You must make sure pdb
+/// is not used by others before calling this method.
+/// You can close the underlying database of a container and assign 
+/// another database with right configurations to it, if the configuration
+/// is not suitable for the container, there will be an 
+/// InvalidArgumentException type of exception thrown.
+/// You can't use the container after you called close_db and before setting 
+/// another valid database handle to the container via 
+/// db_container::set_db_handle() function.
+/// \param pdb The database handle to close.
+_exported void close_db(Db *pdb);
+
+/// Close all open database handles regardless of reference count.
+/// You can't use any container after you called close_all_dbs and 
+/// before setting another valid database handle to the 
+/// container via db_container::set_db_handle() function.
+/// \sa close_db(Db *);
+_exported void close_all_dbs();
+
+/// \brief Close specified database environment handle regardless of reference 
+/// count. 
+///
+/// Make sure the environment is not used by any other databases.
+/// \param pdbenv The database environment handle to close.
+_exported void close_db_env(DbEnv *pdbenv);
+
+/// \brief Close all open database environment handles regardless of
+/// reference count.
+///
+/// You can't use the container after you called close_db and before setting
+/// another valid database handle to the container via 
+/// db_container::set_db_handle() function. \sa close_db_env(DbEnv *);
+_exported void close_all_db_envs();
+//@}
+
+/// \name Transaction control global functions.
+/// dbstl transaction API. You should call these API rather than DB C/C++
+/// API to use Berkeley DB transaction features.
+//@{ 
+/// Begin a new transaction from the specified environment "env". 
+/// This function is called by dbstl user to begin an external transaction.
+/// The "flags" parameter is passed to DbEnv::txn_begin(). 
+/// If a transaction created from 
+/// the same database environment already exists and is unresolved,
+/// the new transaction is started as a child transaction of that transaction,
+/// and thus you can't specify the parent transaction.
+/// \param env The environment to start a transaction from.
+/// \param flags It is set to DbEnv::txn_begin() function.
+/// \return The newly created transaction.
+///
+_exported DbTxn* begin_txn(u_int32_t flags, DbEnv *env);
+
+/// Commit current transaction opened in the environment "env".
+/// This function is called by user to commit an external explicit transaction.
+/// \param env The environment whose current transaction is to be committed.
+/// \param flags It is set to DbTxn::commit() funcion.
+/// \sa commit_txn(DbEnv *, DbTxn *, u_int32_t);
+///
+_exported void commit_txn(DbEnv *env, u_int32_t flags = 0);
+
+/// Commit a specified transaction and all its child transactions.
+/// \param env The environment where txn is started from.
+/// \param txn The transaction to commit, can be a parent transaction of a 
+/// nested transaction group, all un-aborted child transactions of 
+/// it will be committed. 
+/// \param flags It is passed to each DbTxn::commit() call.
+/// \sa commit_txn(DbEnv *, u_int32_t);
+_exported void commit_txn(DbEnv *env, DbTxn *txn, u_int32_t flags = 0);
+
+/// Abort current transaction of environment "env". This function is called by
+/// dbstl user to abort an outside explicit transaction.
+/// \param env The environment whose current transaction is to be aborted.
+/// \sa abort_txn(DbEnv *, DbTxn *);
+_exported void abort_txn(DbEnv *env);
+
+/// Abort specified transaction "txn" and all its child transactions. 
+/// That is, "txn" can be a parent transaction of a nested transaction group.
+/// \param env The environment where txn is started from.
+/// \param txn The transaction to abort, can be a parent transaction of a 
+/// nested transaction group, all child transactions of it will be aborted.
+/// \sa abort_txn(DbEnv *);
+///
+_exported void abort_txn(DbEnv *env, DbTxn *txn);
+
+/// Get current transaction of environment "env".
+/// \param env The environment whose current transaction we want to get.
+/// \return Current transaction of env.
+_exported DbTxn* current_txn(DbEnv *env);
+
+/// Set environment env's current transaction handle to be newtxn. The original
+/// transaction handle returned without aborting or commiting. This function
+/// is used for users to use one transaction among multiple threads.
+/// \param env The environment whose current transaction to replace.
+/// \param newtxn The new transaction to be as the current transaction of env.
+/// \return The old current transaction of env. It is not resolved.
+_exported DbTxn* set_current_txn_handle(DbEnv *env, DbTxn *newtxn);
+//@} 
+
+/// \name Functions to open and register database/environment handles.
+//@{ 
+/// Register a Db handle "pdb1". This handle and handles opened in it will be
+/// closed by ResourceManager, so application code must not try to close or
+/// delete it. Users can do enough configuration before opening the Db then
+/// register it via this function.
+/// All database handles should be registered via this function in each 
+/// thread using the handle. The only exception is the database handle opened
+/// by dbstl::open_db should not be registered in the thread of the 
+/// dbstl::open_db call.
+/// \param pdb1 The database handle to register into dbstl for current thread.
+///
+_exported void register_db(Db *pdb1);
+
+/// Register a DbEnv handle env1, this handle and handles opened in it will be
+/// closed by ResourceManager. Application code must not try to close or delete
+/// it. Users can do enough config before opening the DbEnv and then register
+/// it via this function.
+/// All environment handles should be registered via this function in each 
+/// thread using the handle. The only exception is the environment handle 
+/// opened by dbstl::open_db_env should not be registered in the thread of 
+/// the dbstl::open_db_env call.
+/// \param env1 The environment to register into dbstl for current thread.
+///
+_exported void register_db_env(DbEnv *env1);
+
+/// Helper function to open a database and register it into dbstl for the 
+/// calling thread.
+/// Users still need to register it in any other thread using it if it
+/// is shared by multiple threads, via register_db() function.
+/// Users don't need to delete or free the memory of the returned object, 
+/// dbstl will take care of that.
+/// When you don't use dbstl::open_db() but explicitly call DB C++ API to
+/// open a database, you must new the Db object, rather than create it 
+/// on stack, and you must delete the Db object by yourself.
+/// \param penv The environment to open the database from.
+/// \param cflags The create flags passed to Db class constructor.
+/// \param filename The database file name, passed to Db::open.
+/// \param dbname The database name, passed to Db::open.
+/// \param dbtype The database type, passed to Db::open.
+/// \param oflags The database open flags, passed to Db::open.
+/// \param mode The database open mode, passed to Db::open.
+/// \param txn The transaction to open the database from, passed to Db::open.
+/// \param set_flags The flags to be set to the created database handle.
+/// \return The opened database handle.
+/// \sa register_db(Db *);
+/// \sa open_db_env;
+///
+_exported Db* open_db (DbEnv *penv, const char *filename, DBTYPE dbtype,
+    u_int32_t oflags, u_int32_t set_flags, int mode = 0644, DbTxn *txn = NULL,
+    u_int32_t cflags = 0, const char* dbname = NULL);
+
+/// Helper function to open an environment and register it into dbstl for the
+/// calling thread. Users still need to register it in any other thread if it
+/// is shared by multiple threads, via register_db_env() function above.
+/// Users don't need to delete or free the memory of the returned object, 
+/// dbstl will take care of that.
+/// 
+/// When you don't use dbstl::open_env() but explicitly call DB C++ API to
+/// open an environment, you must new the DbEnv object, rather than create it
+/// on stack, and you must delete the DbEnv object by yourself.
+/// \param env_home Environment home directory, it must exist. Passed to 
+/// DbEnv::open.
+/// \param cflags DbEnv constructor creation flags, passed to DbEnv::DbEnv.
+/// \param set_flags Flags to set to the created environment before opening it.
+/// \param oflags Environment open flags, passed to DbEnv::open.
+/// \param mode Environment region files mode, passed to DbEnv::open.
+/// \param cachesize Environment cache size, by default 4M bytes.
+/// \return The opened database environment handle.
+/// \sa register_db_env(DbEnv *); 
+/// \sa open_db;
+///
+_exported DbEnv* open_env(const char *env_home, u_int32_t set_flags,
+    u_int32_t oflags = DB_CREATE | DB_INIT_MPOOL,
+    u_int32_t cachesize = 4 * 1024 * 1024,
+    int mode = 0644,
+    u_int32_t cflags = 0/* Flags for DbEnv constructor. */);
+//@}
+
+/// @name Mutex API based on Berkeley DB mutex.
+/// These functions are in-process mutex support which uses Berkeley DB 
+/// mutex mechanisms. You can call these functions to do portable 
+/// synchronization for your code.
+//@{
+/// Allocate a Berkeley DB mutex.
+/// \return Berkeley DB mutex handle.
+_exported db_mutex_t alloc_mutex();
+/// Lock a mutex, wait if it is held by another thread.
+/// \param mtx The mutex handle to lock.
+/// \return 0 if succeed, non-zero otherwise, call db_strerror to get message.
+_exported int lock_mutex(db_mutex_t mtx);
+/// Unlock a mutex, and return immediately.
+/// \param mtx The mutex handle to unlock.
+/// \return 0 if succeed, non-zero otherwise, call db_strerror to get message.
+_exported int unlock_mutex(db_mutex_t mtx);
+/// Free a mutex, and return immediately.
+/// \param mtx The mutex handle to free.
+/// \return 0 if succeed, non-zero otherwise, call db_strerror to get message.
+_exported void free_mutex(db_mutex_t mtx);
+//@}
+
+/// Close cursors opened in dbp1.
+/// \param dbp1 The database handle whose active cursors to close.
+/// \return The number of cursors closed by this call.
+_exported size_t close_db_cursors(Db* dbp1);
+
+/// \name Other global functions.
+//@{
+/// If there are multiple threads within a process that make use of dbstl, then
+/// this function should be called in a single thread mutual exclusively before
+/// any use of dbstl in a process; Otherwise, you don't need to call it, but
+/// are allowed to call it anyway.
+_exported void dbstl_startup();
+
+/// This function releases any memory allocated in the heap by code of dbstl.
+/// So you can only call dbstl_exit() right before the entire process exits.
+/// It will release any memory allocated by dbstl that have to live during
+/// the entire process lifetime.
+_exported void dbstl_exit();
+
+/// Operators to compare two Dbt objects.
+/// \param d1 Dbt object to compare.
+/// \param d2 Dbt object to compare.
+_exported bool operator==(const Dbt&d1, const Dbt&d2);
+/// Operators to compare two DBT objects.
+/// \param d1 DBT object to compare.
+/// \param d2 DBT object to compare.
+_exported bool operator==(const DBT&d1, const DBT&d2);
+
+/// If exisiting random temporary database name generation mechanism is still
+/// causing name clashes, users can set this global suffix number which will
+/// be append to each temporary database file name and incremented after each
+/// append, and by default it is 0.
+/// \param num Starting number to append to each temporary db file name.
+_exported void set_global_dbfile_suffix_number(u_int32_t num);
+//@}
+
+//@} // dbstl_global_functions
+
+// Internally used memory allocation functions, they will throw an exception
+// of NotEnoughMemoryException if can't allocate memory.
+_exported void * DbstlReAlloc(void *ptr, size_t size);
+_exported void * DbstlMalloc(size_t size);
+
+_exported u_int32_t hash_default(Db * /*dbp*/, const void *key, u_int32_t len);
+
+// Default string manipulation callbacks.
+_exported u_int32_t dbstl_strlen(const char *str);
+_exported void dbstl_strcpy(char *dest, const char *src, size_t num);
+_exported int dbstl_strncmp(const char *s1, const char *s2, size_t num);
+_exported int dbstl_strcmp(const char *s1, const char *s2);
+_exported int dbstl_wcscmp(const wchar_t *s1, const wchar_t *s2);
+_exported int dbstl_wcsncmp(const wchar_t *s1, const wchar_t *s2, size_t num);
+_exported u_int32_t dbstl_wcslen(const wchar_t *str);
+_exported void dbstl_wcscpy(wchar_t *dest, const wchar_t *src, size_t num);
+
+END_NS
+
+//////////////////////////////////////////////////////////////////
+// End of public global function declarations.
+//////////////////////////////////////////////////////////////////
+
+#endif /* !_DB_STL_COMMON_H */
diff --git a/stl/dbstl_container.cpp b/stl/dbstl_container.cpp
new file mode 100644
index 0000000..4543f79
--- /dev/null
+++ b/stl/dbstl_container.cpp
@@ -0,0 +1,520 @@
+/*-
+ * See the file LICENSE for redistribution information.
+ *
+ * Copyright (c) 2009 Oracle.  All rights reserved.
+ *
+ * $Id$
+ */
+
+#include <string>
+
+#include "dbstl_container.h"
+#include "dbstl_resource_manager.h"
+#include "dbstl_exception.h"
+#include "dbstl_utility.h"
+#include "dbstl_inner_utility.h"
+
+typedef struct {
+	time_t	tv_sec;				/* seconds */
+	long	tv_nsec;			/* nanoseconds */
+} db_timespec;
+
+extern "C"{
+void __os_id (DB_ENV *, pid_t *, db_threadid_t*);
+void __os_gettime(ENV *env, db_timespec *tp, int monotonic);
+}
+
+START_NS(dbstl)
+
+using std::string;
+u_int32_t db_container::g_db_file_suffix_ = 0;
+
+void set_global_dbfile_suffix_number(u_int32_t num)
+{
+	db_container::g_db_file_suffix_ = num;
+}
+
+// Internally used memory allocation functions, they will throw an exception
+// of NotEnoughMemoryException if can't allocate memory.
+void *DbstlReAlloc(void *ptr, size_t size)
+{
+	void *p;
+
+	assert(size != 0);
+	if ((p = realloc(ptr, size)) == NULL)
+		THROW(NotEnoughMemoryException, 
+		    ("DbstlReAlloc failed to allocate memory", size));
+
+	return p;
+}
+
+void *DbstlMalloc(size_t size)
+{
+	void *p;
+
+	assert(size != 0);
+	if ((p = malloc(size)) == NULL)
+		THROW(NotEnoughMemoryException, 
+		    ("DbstlMalloc failed to allocate memory", size));
+	return p;
+}
+
+void db_container::init_members()
+{
+	txn_begin_flags_ = 0; 
+	commit_flags_ = 0; 
+	cursor_oflags_ = 0; 
+	pdb_ = NULL;
+	is_set_ = false;
+	auto_commit_ = false; 
+	dbenv_ = NULL;
+}
+
+void db_container::init_members(Db *dbp, DbEnv *envp)
+{
+	txn_begin_flags_ = 0; 
+	commit_flags_ = 0; 
+	is_set_ = false;
+	cursor_oflags_ = 0; 
+	pdb_ = dbp;
+	dbenv_ = envp;
+	set_auto_commit(pdb_);
+}
+
+db_container::db_container()
+{
+	init_members();
+}
+
+db_container::db_container(const db_container& dbctnr)
+{
+	init_members(dbctnr);
+}
+
+db_container::db_container(Db *dbp, DbEnv *envp) 
+{
+	init_members(dbp, envp);
+}
+
+void db_container::init_members(const db_container&dbctnr)
+{
+	txn_begin_flags_ = dbctnr.txn_begin_flags_; 
+	commit_flags_ = dbctnr.commit_flags_; 
+	cursor_oflags_ = dbctnr.cursor_oflags_; 
+	// We don't copy database handles because we will clone another 
+	// database from dbctnr's db, and get its handle. We will 
+	// copy the following database properties because they will be
+	// definitely identical.
+	//
+	pdb_ = NULL;
+	is_set_ = dbctnr.is_set_;
+	auto_commit_ = dbctnr.auto_commit_; 
+	dbenv_ = dbctnr.dbenv_;
+}
+void db_container::open_db_handles(Db *&pdb, DbEnv *&penv, DBTYPE dbtype, 
+    u_int32_t oflags, u_int32_t sflags)
+{
+	if (pdb == NULL) {
+		pdb = open_db(penv, NULL, dbtype, oflags, sflags);
+		this->pdb_ = pdb;
+	}
+
+	if (penv == NULL) {
+		penv = pdb->get_env();
+		this->dbenv_ = penv;
+		set_auto_commit(pdb_);
+	}
+}
+
+Db* db_container::clone_db_config(Db *dbp)
+{
+	string str;
+
+	return clone_db_config(dbp, str);
+}
+
+// Open a new db with identical configuration to dbp. The dbfname brings 
+// back the generated db file name.
+Db* db_container::clone_db_config(Db *dbp, string &dbfname)
+{
+	Db *tdb = NULL;
+	int ret;
+	DBTYPE dbtype;
+	u_int32_t oflags, sflags;
+	const char *dbfilename, *dbname, *tdbname;
+
+	BDBOP2(dbp->get_type(&dbtype), ret, dbp->close(0));
+	BDBOP2(dbp->get_open_flags(&oflags), ret, dbp->close(0));
+	BDBOP2(dbp->get_flags(&sflags), ret, dbp->close(0));
+	
+	BDBOP (dbp->get_dbname(&dbfilename, &dbname), ret);
+	if (dbfilename == NULL) {
+		tdb = open_db(dbp->get_env(), 
+		    dbfilename, dbtype, oflags, sflags, 0420, NULL, 0, dbname);
+		dbfname.assign("");
+
+	} else {
+		construct_db_file_name(dbfname);
+		tdbname = dbfname.c_str();
+		tdb = open_db(dbp->get_env(), tdbname, dbtype, oflags, sflags);
+	}
+
+	return tdb;
+}
+
+int db_container::construct_db_file_name(string &filename) const
+{
+	db_threadid_t tid;
+	db_timespec ts;
+	int len;
+	char name[64];
+
+	__os_gettime(NULL, &ts, 1);
+	__os_id(NULL, NULL, &tid);
+
+	// avoid name clash
+	len = _snprintf(name, 64, "tmpdb_db_map_%lu_%d_%u.db", 
+	    (u_long)((uintptr_t)tid + ts.tv_nsec), rand(), g_db_file_suffix_++);
+	filename = name;
+
+	return 0;
+}
+
+void db_container::set_auto_commit(Db *db) 
+{
+	u_int32_t envof, envf, dbf;
+
+	if (db == NULL || dbenv_ == NULL) {
+		auto_commit_ = false;
+		return;
+	}
+
+	dbenv_->get_open_flags(&envof);
+	if ((envof & DB_INIT_TXN) == 0) {
+		this->auto_commit_ = false;
+	} else {
+		dbenv_->get_flags(&envf);
+		db->get_flags(&dbf);
+		if (((envf & DB_AUTO_COMMIT) != 0) || 
+		    ((dbf & DB_AUTO_COMMIT) != 0))
+			this->auto_commit_ = true;
+		else
+			this->auto_commit_ = false;
+	}
+}
+
+void db_container::set_db_handle(Db *dbp, DbEnv *newenv)
+{
+	const char *errmsg;
+
+	if ((errmsg = verify_config(dbp, newenv)) != NULL) {
+		THROW(InvalidArgumentException, ("Db*", errmsg));
+		
+	}
+
+	pdb_ = dbp;
+	if (newenv)
+		dbenv_ = newenv;
+	
+}
+
+void db_container::verify_db_handles(const db_container &cntnr) const
+{
+	Db *pdb2 = cntnr.get_db_handle();
+	const char *home = NULL, *home2 = NULL, *dbf = NULL, *dbn = NULL,
+	    *dbf2 = NULL, *dbn2 = NULL;
+	int ret = 0;
+	u_int32_t flags = 0, flags2 = 0;
+	bool same_dbfile, same_dbname, anonymous_inmemdbs;
+	// Check the two database handles do not refer to the same database.
+	// If they don't point to two anonymous databases at the same time,
+	// then two identical file names and two identical database names 
+	// mean the two databases are the same.
+	assert(this->pdb_ != pdb2);
+	if (pdb_ == NULL)
+		return;
+
+	BDBOP(pdb_->get_dbname(&dbf, &dbn), ret);
+	BDBOP(pdb2->get_dbname(&dbf2, &dbn2), ret);
+
+	anonymous_inmemdbs = (dbf == NULL && dbf2 == NULL && 
+	    dbn == NULL && dbn2 == NULL);
+
+	same_dbfile = (dbf != NULL && dbf2 != NULL && (strcmp(dbf, dbf2) == 0))
+	    || (dbf == NULL && dbf2 == NULL);
+
+	same_dbname = (dbn == NULL && dbn2 == NULL) ||
+	    (dbn != NULL && dbn2 != NULL && strcmp(dbn, dbn2) == 0);
+
+	assert((!(anonymous_inmemdbs) && same_dbfile && same_dbname) == false);
+
+	// If any one of the two environments are transactional, both of them
+	// should be opened in the same transactional environment.
+	DbEnv *penv2 = cntnr.get_db_env_handle();
+	if (dbenv_ != penv2 ){
+		BDBOP(this->dbenv_->get_open_flags(&flags), ret);
+		BDBOP(penv2->get_open_flags(&flags2), ret);
+
+		if ((flags & DB_INIT_TXN) || (flags2 & DB_INIT_TXN)) {
+			BDBOP(dbenv_->get_home(&home), ret);
+			BDBOP(penv2->get_home(&home), ret);
+			assert(home != NULL && home2 != NULL && 
+			    strcmp(home, home2) == 0);
+		}
+	}
+}
+
+bool operator==(const Dbt&d1, const Dbt&d2)  
+{
+	if (d1.get_size() != d2.get_size())
+		return false;
+
+	return memcmp(d1.get_data(), d2.get_data(), 
+	    d2.get_size()) == 0;
+}
+
+bool operator==(const DBT&d1, const DBT&d2)  
+{
+	if (d1.size != d2.size)
+		return false;
+	return memcmp(d1.data, d2.data, d2.size) == 0;
+}
+
+void close_all_dbs()
+{
+	ResourceManager::instance()->close_all_dbs();
+}
+
+void close_db(Db *pdb) 
+{
+	ResourceManager::instance()->close_db(pdb);
+}
+
+DbTxn* begin_txn(u_int32_t flags, DbEnv*env) 
+{
+	return ResourceManager::instance()->begin_txn(flags, env, 1);
+}
+
+void commit_txn(DbEnv *env, u_int32_t flags) 
+{
+	ResourceManager::instance()->commit_txn(env, flags);
+}
+
+void commit_txn(DbEnv *env, DbTxn *txn, u_int32_t flags) 
+{
+	ResourceManager::instance()->commit_txn(env, txn, flags);
+}
+
+void abort_txn(DbEnv *env)
+{
+	ResourceManager::instance()->abort_txn(env);
+}
+
+void abort_txn(DbEnv *env, DbTxn *txn)
+{
+	ResourceManager::instance()->abort_txn(env, txn);
+}
+
+DbTxn* current_txn(DbEnv *env)
+{
+	return ResourceManager::instance()->current_txn(env);
+}
+
+DbTxn* set_current_txn_handle(DbEnv *env, DbTxn *newtxn)
+{
+	return ResourceManager::instance()->
+	    set_current_txn_handle(env, newtxn);
+}
+
+void register_db(Db *pdb1)
+{
+	ResourceManager::instance()->register_db(pdb1);
+}
+
+void register_db_env(DbEnv *env1) 
+{
+	ResourceManager::instance()->register_db_env(env1);
+}
+
+Db* open_db (DbEnv *penv, const char *filename, DBTYPE dbtype, 
+    u_int32_t oflags, u_int32_t set_flags, int mode, 
+    DbTxn *txn, u_int32_t cflags, const char *dbname) 
+{
+	return ResourceManager::instance()->open_db(
+	    penv, filename, dbtype, oflags, set_flags, mode, txn, 
+	    cflags, dbname);
+}
+
+DbEnv* open_env(const char *env_home, u_int32_t set_flags,
+    u_int32_t oflags, u_int32_t cachesize, int mode, u_int32_t cflags)
+{
+	return ResourceManager::instance()->open_env(
+	    env_home, set_flags, oflags, cachesize, mode, cflags);
+}
+
+void close_db_env(DbEnv *pdbenv)
+{
+
+	ResourceManager::instance()->close_db_env(pdbenv);
+}
+
+void close_all_db_envs()
+{
+	ResourceManager::instance()->close_all_db_envs();
+}
+
+size_t close_db_cursors(Db *dbp1)
+{
+	return ResourceManager::instance()->close_db_cursors(dbp1);
+}
+
+db_mutex_t alloc_mutex() 
+{
+	int ret;
+	db_mutex_t mtx;
+
+	BDBOP2(ResourceManager::instance()->get_mutex_env()->mutex_alloc(
+	    DB_MUTEX_PROCESS_ONLY, &mtx), ret, ResourceManager::
+	    instance()->get_mutex_env()->mutex_free(mtx));
+	return mtx;
+}
+
+int lock_mutex(db_mutex_t mtx)
+{
+	int ret;
+
+	BDBOP2(ResourceManager::instance()->global_lock(mtx), ret, 
+	    ResourceManager::
+	    instance()->get_mutex_env()->mutex_free(mtx));
+	return 0;
+}
+
+int unlock_mutex(db_mutex_t mtx)
+{
+	int ret;
+
+	BDBOP2(ResourceManager::instance()->global_unlock(mtx), ret, 
+	    ResourceManager::
+	    instance()->get_mutex_env()->mutex_free(mtx));
+	return 0;
+}
+
+void free_mutex(db_mutex_t mtx)
+{
+	ResourceManager::instance()->get_mutex_env()->mutex_free(mtx);
+}
+
+void dbstl_startup()
+{
+	ResourceManager::instance()->global_startup();
+}
+
+void dbstl_exit()
+{
+	ResourceManager::instance()->global_exit();
+}
+
+// Internally used only.
+void throw_bdb_exception(const char *caller, int error)
+{
+	 switch (error) {
+	 case DB_LOCK_DEADLOCK:
+		 {
+			 DbDeadlockException dl_except(caller);
+			 throw dl_except;
+		 }
+	 case DB_LOCK_NOTGRANTED:
+		 {
+			 DbLockNotGrantedException lng_except(caller);
+			 throw lng_except;
+		 }
+	 case DB_REP_HANDLE_DEAD:
+		 {
+			 DbRepHandleDeadException hd_except(caller);
+			 throw hd_except;
+		 }
+	 case DB_RUNRECOVERY:
+		 {
+			 DbRunRecoveryException rr_except(caller);
+			 throw rr_except;
+		 }
+	 default:
+		 {
+			 DbException except(caller, error);
+			 throw except;
+		 }
+	 }
+}
+
+void register_global_object(DbstlGlobalInnerObject *gio)
+{
+	ResourceManager::instance()->register_global_object(gio);
+}
+
+u_int32_t hash_default(Db * /* dbp */, const void *key, u_int32_t len)
+{
+	const u_int8_t *k, *e;
+	u_int32_t h;
+
+	k = (const u_int8_t *)key;
+	e = k + len;
+	for (h = 0; k < e; ++k) {
+		h *= 16777619;
+		h ^= *k;
+	}
+	return (h);
+}
+
+bool DbstlMultipleDataIterator::next(Dbt &data)
+{
+	if (*p_ == (u_int32_t)-1) {
+		data.set_data(0);
+		data.set_size(0);
+		p_ = 0;
+	} else {
+		data.set_data(data_ + *p_--);
+		data.set_size(*p_--);
+		if (data.get_size() == 0 && data.get_data() == data_)
+			data.set_data(0);
+	}
+	return (p_ != 0);
+}
+
+bool DbstlMultipleKeyDataIterator::next(Dbt &key, Dbt &data)
+{
+	if (*p_ == (u_int32_t)-1) {
+		key.set_data(0);
+		key.set_size(0);
+		data.set_data(0);
+		data.set_size(0);
+		p_ = 0;
+	} else {
+		key.set_data(data_ + *p_);
+		p_--;
+		key.set_size(*p_);
+		p_--;
+		data.set_data(data_ + *p_);
+		p_--;
+		data.set_size(*p_);
+		p_--;
+	}
+	return (p_ != 0);
+}
+
+bool DbstlMultipleRecnoDataIterator::next(db_recno_t &recno, Dbt &data)
+{
+	if (*p_ == (u_int32_t)0) {
+		recno = 0;
+		data.set_data(0);
+		data.set_size(0);
+		p_ = 0;
+	} else {
+		recno = *p_--;
+		data.set_data(data_ + *p_--);
+		data.set_size(*p_--);
+	}
+	return (p_ != 0);
+}
+
+END_NS
+
diff --git a/stl/dbstl_container.h b/stl/dbstl_container.h
new file mode 100644
index 0000000..279fe40
--- /dev/null
+++ b/stl/dbstl_container.h
@@ -0,0 +1,582 @@
+/*-
+ * See the file LICENSE for redistribution information.
+ *
+ * Copyright (c) 2009 Oracle.  All rights reserved.
+ *
+ * $Id$
+ */
+
+#ifndef _DB_STL_CONTAINER_H__
+#define _DB_STL_CONTAINER_H__
+
+#include "dbstl_common.h"
+#include "dbstl_resource_manager.h"
+#include <assert.h>
+
+START_NS(dbstl)
+
+class ResourceManager;
+
+//////////////////////////////////////////////////////////////////////////
+//////////////////////////////////////////////////////////////////////////
+//
+// db_container class definition
+//
+// This class's begin_txn, commit/abort_txn is used to wrap each DB related
+// operation inside dbstl. When auto commit is enabled, each operation will
+// be auto committed before returning, and aborted when an exception is thrown.
+//
+// It also contains members to hold all needed parameters and flags for
+// transaction and cursor related calls.
+//
+// Container classes will inherit from this class. Each container will enclose
+// every db related operation with db_container::begin_txn and
+// db_container::commit_txn, and if exception is not caught, abort_txn()
+// should be called.
+
+/** \defgroup dbstl_containers dbstl container classes
+A dbstl container is very much like a C++ STL container. It stores a 
+collection of data items, or key/data pairs. 
+Each container is backed by a Berkeley DB database created in an explicit
+database environment or an internal private environment; And the database
+itself can be created explicitly with all kinds of configurations, or
+by dbstl internally. For each type of container, some specific type of 
+database and/or configurations must be used or specified to the database
+and its environment. dbstl will check the database and environment conform 
+to the requirement. When users don't have a chance to specify a container's
+backing database and environment, like in copy constructors, dbstl will
+create proper databases and/or environment for it. There are two helper 
+functions to make it easier to create/open an environment or database, they
+are dbstl::open_db() and dbstl::open_env();
+\sa dbstl::open_db() dbstl::open_env() db_vector db_map db_multimap db_set 
+db_multiset
+*/
+
+/** \ingroup dbstl_containers
+@{
+This class is the base class for all db container classes, you don't directly
+use this class, but all container classes inherit from this class, so you need
+to know the methods that can be accessed via concrete container classes.
+This class is also used to support auto commit transactions. Autocommit is
+enabled when DB_AUTO_COMMIT is set to the database or database environment
+handle and the environment is transactional.
+
+Inside dbstl, there are transactions begun and committed/aborted if the backing
+database and/or environment requires auto commit, and there are cursors
+opened internally, and you can set the flags used by the transaction and cursor
+functions via set functions of this class.
+
+All dbstl containers are fully multi-threaded, you should not need any
+synchronization to use them in the correct way, but this class is not thread
+safe, access to its members are not proctected by any mutex because the data
+members of this class are supposed to be set before they are used, 
+and remain read only afterwards. If this is not the case, you must synchronize
+the access.
+*/
+class _exported db_container
+{
+private:
+	// By default these flags are 0, users should configure these values
+	// on container initialization.
+	//
+	u_int32_t txn_begin_flags_, commit_flags_;
+	mutable u_int32_t cursor_oflags_;
+
+	// Berkeley DB database handle for each container. Subclasses do not
+	// need to define it.
+	//
+	Db *pdb_;
+
+	// Berkeley DB environment handle in which the db handle is opened.
+	DbEnv *dbenv_;
+
+	// db_map_iterator<> needs to know whether the container is a
+	// db_(multi)set or not
+	//
+	bool is_set_;
+
+	// Determined automatically, by inspecting users the Berkeley DB
+	// database and environment configuration options.
+	//
+	bool auto_commit_;
+
+	// If exisiting random temporary database name generation mechanism is
+	// still causing name clashes, users can set this global suffix number
+	// which will be append to each temporary database file name and by 
+	// default it is 0. there is a dbstl::set_global_dbfile_suffix_number
+	// to do so.
+	static u_int32_t g_db_file_suffix_;
+	friend void set_global_dbfile_suffix_number(u_int32_t);
+protected:
+
+	// Does not clone or copy data from database parameter.
+	// Return the db file name back in the dbfname parameter.
+	// We construct a default database name the user can rename it using
+	// either DbEnv::dbrename or Db::rename.
+	//
+	Db* clone_db_config(Db *dbp, std::string &dbfname);
+	Db* clone_db_config(Db *dbp);
+
+	// Store the name into name parameter whose length is n. Return -1 if
+	// not enough space.
+	int construct_db_file_name(std::string &filename) const;
+
+	// Check that this container and cntnr are backed by different databases
+	// and if any one of them is using transactions, both should be in the
+	// same transactional environment.
+	// Called by all deriving classes' methods
+	// which have a container parameter.
+	void verify_db_handles(const db_container &cntnr) const;
+
+	void open_db_handles(Db *&pdb, DbEnv *&penv, DBTYPE dbtype,
+	    u_int32_t oflags, u_int32_t sflags);
+
+	inline void set_is_set(bool b)
+	{
+		is_set_ = b;
+	}
+
+	inline bool is_set() const
+	{
+		return is_set_;
+	}
+
+	// Database and environment handles and autocommit and is_set_ are 
+	// not assigned, because they are the nature of my own db, not 
+	// that of dbctnr.
+	inline const db_container &operator=(const db_container & dbctnr)
+	{
+		ASSIGNMENT_PREDCOND(dbctnr)
+		txn_begin_flags_ = dbctnr.txn_begin_flags_;
+		commit_flags_ = dbctnr.commit_flags_;
+		cursor_oflags_ = dbctnr.cursor_oflags_;
+		return dbctnr;
+	}
+
+public:
+	/// Default constructor.
+	db_container();
+
+	/// Copy constructor.
+	/// The new container will be backed by another database within the
+	/// same environment unless dbctnr's backing database is in its own
+	/// internal private environment. The name of the database is coined
+	/// based on current time and thread id and some random number. If
+	/// this is still causing naming clashes, you can set a suffix number
+	/// via "set_global_dbfile_suffix_number" function; And following db
+	/// file will suffix this number in the file name for additional 
+	/// randomness. And the suffix will be incremented after each such use.
+	/// You can change the file name via DbEnv::rename.
+	/// If dbctnr is using an anonymous database, the newly constructed
+	/// container will also use an anonymous one.
+	/// \param dbctnr The container to initialize this container.
+	db_container(const db_container &dbctnr);
+
+	/**
+	This constructor is not directly called by the user, but invoked by
+	constructors of concrete container classes. The statement about the
+	parameters applies to constructors of all container classes.
+	\param dbp Database handle. dbp is supposed to be opened inside envp.
+	Each dbstl container is backed by a Berkeley DB database, so dbstl 
+	will create an internal anonymous database if dbp is NULL. 
+	\param envp Environment handle. And envp can also be NULL, meaning the
+	dbp handle may be created in its internal private environment.
+	*/
+	db_container(Db *dbp, DbEnv *envp);
+
+	/// The backing database is not closed in this function. It is closed
+	/// when current thread exits and the database is no longer referenced
+	/// by any other container instances in this process. 
+	/// In order to make the reference counting work alright, you must call
+	/// register_db(Db*) and register_db_env(DbEnv*) correctly.
+	/// \sa register_db(Db*) register_db_env(DbEnv*) 
+	virtual ~db_container(){}
+
+	/// \name Get and set functions for data members.
+	/// Note that these functions are not thread safe, because all data 
+	/// members of db_container are supposed to be set on container 
+	/// construction and initialization, and remain read only afterwards.
+	//@{
+	/// Get the backing database's open flags.
+	/// \return The backing database's open flags.
+	inline u_int32_t get_db_open_flags()   const
+	{
+		u_int32_t oflags;
+		pdb_->get_open_flags(&oflags);
+		return oflags;
+	}
+
+	/// Get the backing database's flags that are set via Db::set_flags()
+	/// function.
+	/// \return Flags set to this container's database handle.
+	inline u_int32_t get_db_set_flags()   const
+	{
+		u_int32_t oflags;
+		pdb_->get_flags(&oflags);
+		return oflags;
+	}
+
+	/// Get the backing database's handle. 
+	/// \return The backing database handle of this container.
+	inline Db* get_db_handle() const
+	{
+		return pdb_;
+	}
+
+	/// Get the backing database environment's handle. 
+	/// \return The backing database environment handle of this container.
+	inline DbEnv* get_db_env_handle()  const
+	{
+		return dbenv_;
+	}
+
+	/** 
+	Set the underlying database's handle, and optionally environment 
+	handle if the environment has also changed. That is, users can change
+	the container object's underlying database while the object is alive.
+	dbstl will verify that the handles set conforms to the concrete 
+	container's requirement to Berkeley DB database/environment handles.
+	\param dbp The database handle to set.
+	\param newenv The database environment handle to set.
+	*/
+	void set_db_handle(Db *dbp, DbEnv *newenv = NULL);
+
+	/** Set the flags required by the Berkeley DB functions 
+	DbEnv::txn_begin(), DbTxn::commit() and DbEnv::cursor(). These flags
+	will be set to this container's auto commit member functions when 
+	auto commit transaction is used, except that cursor_oflags is set to 
+	the Dbc::cursor when creating an iterator for this container.
+	By default the three flags are all zero.
+	You can also set the values of the flags individually by using the 
+	appropriate set functions in this class. The corresponding get 
+	functions return the flags actually used.
+	\param txn_begin_flags Flags to be set to DbEnv::txn_begin().
+	\param commit_flags Flags to be set to DbTxn::commit().
+	\param cursor_open_flags Flags to be set to Db::cursor().
+	*/
+	inline void set_all_flags(u_int32_t txn_begin_flags,
+	    u_int32_t commit_flags, u_int32_t cursor_open_flags)
+	{
+		this->txn_begin_flags_ = txn_begin_flags;
+		this->commit_flags_ = commit_flags;
+		this->cursor_oflags_ = cursor_open_flags;
+	}
+
+	/// Set flag of DbEnv::txn_begin() call.
+	/// \param flag Flags to be set to DbEnv::txn_begin().
+	inline void set_txn_begin_flags(u_int32_t flag )
+	{
+		txn_begin_flags_ = flag;
+	}
+
+	/// Get flag of DbEnv::txn_begin() call.
+	/// \return Flags to be set to DbEnv::txn_begin().
+	inline u_int32_t get_txn_begin_flags()  const
+	{
+		return txn_begin_flags_;
+	}
+
+	/// Set flag of DbTxn::commit() call.
+	/// \param flag Flags to be set to DbTxn::commit().
+	inline void set_commit_flags(u_int32_t flag)
+	{
+		commit_flags_ = flag;
+	}
+
+	/// Get flag of DbTxn::commit() call.
+	/// \return Flags to be set to DbTxn::commit().
+	inline u_int32_t get_commit_flags()  const
+	{
+		return commit_flags_;
+	}
+
+	/// Get flag of Db::cursor() call.
+	/// \return Flags to be set to Db::cursor().
+	inline u_int32_t get_cursor_open_flags()  const
+	{
+		return cursor_oflags_;
+	}
+
+	/// Set flag of Db::cursor() call.
+	/// \param flag Flags to be set to Db::cursor().
+	inline void set_cursor_open_flags(u_int32_t flag)
+	{
+		cursor_oflags_ = flag;
+	}
+	//@} // getter_setters
+
+protected:
+	void init_members();
+	void init_members(Db *pdb, DbEnv *env);
+	void init_members(const db_container&cnt);
+	// Called internally by concrete container constructors. Verification
+	// is done by the specialized constructors
+	void set_db_handle_int(Db *dbp, DbEnv *envp)
+	{
+		this->pdb_ = dbp;
+		this->dbenv_ = envp;
+	}
+
+	// Child classes override this function to check the db and environment
+	// handles are correctly configured.
+	virtual const char* verify_config(Db* pdb, DbEnv* penv) const
+	{
+		if (pdb != NULL && ((pdb->get_create_flags() & 
+		    DB_CXX_NO_EXCEPTIONS) == 0))
+			return 
+"Db and DbEnv object must be constructed with DB_CXX_NO_EXCEPTIONS flag set.";
+
+		if (penv != NULL && ((penv->get_create_flags() & 
+		    DB_CXX_NO_EXCEPTIONS) == 0))
+			return 
+"Db and DbEnv object must be constructed with DB_CXX_NO_EXCEPTIONS flag set.";
+		return NULL;
+	}
+
+	// Use db and dbenv_ to determine whether to enable autocommit. If
+	// DB_AUTOCOMMIT is set on dbenv_ or db and dbenv_ is transactional,
+	// that db should be autocommit.
+	//
+	void set_auto_commit(Db* db);
+
+	// Begin a transaction. Used to make a container's db related
+	// operations auto commit when the operation completes and abort
+	// when the operation fails. If there is already a transaction for this
+	// container's environment, then that transaction is used. If the
+	// transaction was created by DB STL, its reference count is
+	// incremented (user created and external transactions are not
+	// reference counted because they can be nested.).
+	inline DbTxn* begin_txn() const
+	{
+		DbTxn *txn = NULL;
+
+		if (this->auto_commit_) {
+			txn = ResourceManager::instance()->begin_txn(
+			    this->txn_begin_flags_, dbenv_, 0);
+		}
+		return txn;
+	}
+
+	inline void commit_txn()  const
+	{
+		if (this->auto_commit_) {
+			ResourceManager::instance()->
+			    commit_txn(pdb_->get_env(), this->commit_flags_);
+		}
+	}
+
+	inline void abort_txn() const
+	{
+		if (this->auto_commit_)
+			ResourceManager::instance()->
+			    abort_txn(pdb_->get_env());
+	}
+
+	inline DbTxn *current_txn() const
+	{
+		return ResourceManager::instance()->
+		    current_txn(pdb_->get_env());
+	}
+}; // db_container
+/** @} */ // dbstl_containers
+
+/// \addtogroup dbstl_helper_classes
+//@{
+/// Bulk retrieval configuration helper class. Used by the begin() function of
+/// a container.
+class _exported BulkRetrievalOption
+{
+public:
+	enum Option {BulkRetrieval, NoBulkRetrieval};
+
+protected:
+	Option bulk_retrieve;
+	u_int32_t bulk_buf_sz_;
+
+	inline BulkRetrievalOption()
+	{
+		bulk_retrieve = NoBulkRetrieval;
+		bulk_buf_sz_ = DBSTL_BULK_BUF_SIZE;
+	}
+
+public:
+	inline BulkRetrievalOption(Option bulk_retrieve1, 
+	    u_int32_t bulk_buf_sz = DBSTL_BULK_BUF_SIZE)
+	{
+		this->bulk_retrieve = bulk_retrieve1;
+		this->bulk_buf_sz_ = bulk_buf_sz;
+	}
+
+	// The following two static members should best be const, but this is
+	// impossible because in C++ this definition is a function declaration:
+	// const static BulkRetrievalOption BulkRetrieval(BulkRetrieval);
+	// i.e. const static members can only be inited with default copy
+	// constructor.
+	//
+  	// Static data members can't be compiled into a .lib for a dll on
+  	// Windows, code using the static members will have link error---
+  	// unresolved symbols, so we have to use a static function here.
+ 	/// This function indicates that you need a bulk retrieval iterator, 
+ 	/// and it can be also used to optionally set the bulk read buffer size.
+  	inline static BulkRetrievalOption bulk_retrieval(
+  	    u_int32_t bulk_buf_sz = DBSTL_BULK_BUF_SIZE)
+  	{
+  		return BulkRetrievalOption(BulkRetrieval, bulk_buf_sz);
+  	}
+  
+ 	/// This function indicates that you do not need a bulk retrieval 
+ 	/// iterator.
+  	inline static BulkRetrievalOption no_bulk_retrieval()
+  	{
+  		return BulkRetrievalOption(NoBulkRetrieval, 0);
+  	}
+  
+ 	/// Equality comparison.
+  	inline bool operator==(const BulkRetrievalOption& bro) const
+  	{
+  		return bulk_retrieve == bro.bulk_retrieve;
+  	}
+  
+ 	/// Assignment operator.
+  	inline void operator=(BulkRetrievalOption::Option opt)
+  	{
+  		bulk_retrieve = opt;
+  	}
+  
+ 	/// Return the buffer size set to this object.
+ 	inline u_int32_t bulk_buf_size()
+  	{
+  		return bulk_buf_sz_;
+  	}
+};
+//@}
+
+/// \addtogroup dbstl_helper_classes
+//@{
+/// Read-modify-write cursor configuration helper class. Used by each begin()
+/// function of all containers.
+class _exported ReadModifyWriteOption
+{
+protected:
+	enum Option{ReadModifyWrite, NoReadModifyWrite};
+	Option rmw;
+
+	inline ReadModifyWriteOption(Option rmw1)
+	{
+		this->rmw = rmw1;
+	}
+
+	inline ReadModifyWriteOption()
+	{
+		rmw = NoReadModifyWrite;
+	}
+
+public:
+	/// Assignment operator.
+	inline void operator=(ReadModifyWriteOption::Option rmw1)
+	{
+		this->rmw = rmw1;
+	}
+
+	/// Equality comparison.
+	inline bool operator==(const ReadModifyWriteOption &rmw1) const
+	{
+		return this->rmw == rmw1.rmw;
+	}
+
+	/// Call this function to tell the container's begin() function that
+	/// you need a read-modify-write iterator.
+	inline static ReadModifyWriteOption read_modify_write()
+	{
+		return ReadModifyWriteOption(ReadModifyWrite);
+	}
+
+	/// Call this function to tell the container's begin() function that
+	/// you do not need a read-modify-write iterator. This is the default
+	/// value for the parameter of any container's begin() function.
+	inline static ReadModifyWriteOption no_read_modify_write()
+	{
+		return ReadModifyWriteOption(NoReadModifyWrite);
+	}
+
+};
+//@} // dbstl_helper_classes
+
+// The classes in the Berkeley DB C++ API do not expose data and p_ member.
+// Extend the class to provide this functionality, rather than altering the
+// internal implementations.
+//
+class _exported DbstlMultipleIterator : protected DbMultipleIterator
+{
+protected:
+	DbstlMultipleIterator(const Dbt &dbt) : DbMultipleIterator(dbt) {}
+public:
+	u_int32_t get_pointer()
+	{
+		u_int32_t off;
+		off = (u_int32_t)((u_int8_t*)p_ - data_);
+		return off;
+	}
+
+	inline void set_pointer(u_int32_t offset)
+	{
+		p_ = (u_int32_t*)(data_ + offset);
+	}
+
+};
+
+class _exported DbstlMultipleKeyDataIterator : public DbstlMultipleIterator
+{
+public:
+	DbstlMultipleKeyDataIterator(const Dbt &dbt)
+	    : DbstlMultipleIterator(dbt) {}
+	bool next(Dbt &key, Dbt &data);
+};
+
+class _exported DbstlMultipleRecnoDataIterator : public DbstlMultipleIterator
+{
+public:
+	DbstlMultipleRecnoDataIterator(const Dbt &dbt)
+	   : DbstlMultipleIterator(dbt) {}
+	bool next(db_recno_t &recno, Dbt &data);
+};
+
+class _exported DbstlMultipleDataIterator : public DbstlMultipleIterator
+{
+public:
+	DbstlMultipleDataIterator(const Dbt &dbt)
+	    : DbstlMultipleIterator(dbt) {}
+	bool next(Dbt &data);
+};
+
+// These classes are used to give data values meaningful default
+// initializations. They are only necessary for types that do not have a
+// reasonable default constructor - explicitly char *, wchar_t * and T*.
+// The string types don't have a reasonable default initializer since we store
+// the underlying content, not a pointer.
+// So we fully instantiate types for T* and const T* and set the pointers to
+// NULL and leave other types intact.
+template <Typename T>
+class DbstlInitializeDefault
+{
+public:
+	DbstlInitializeDefault(T&){}
+};
+
+template <Typename T>
+class DbstlInitializeDefault<T *>
+{
+public:
+	DbstlInitializeDefault(T *& t){t = NULL;}
+};
+
+template <Typename T>
+class DbstlInitializeDefault<const T *>
+{
+public:
+	DbstlInitializeDefault(const T *& t){t = NULL;}
+};
+
+END_NS
+
+#endif //_DB_STL_CONTAINER_H__
diff --git a/stl/dbstl_dbc.h b/stl/dbstl_dbc.h
new file mode 100644
index 0000000..bcf6695
--- /dev/null
+++ b/stl/dbstl_dbc.h
@@ -0,0 +1,1327 @@
+/*-
+ * See the file LICENSE for redistribution information.
+ *
+ * Copyright (c) 2009 Oracle.  All rights reserved.
+ *
+ * $Id$
+ */
+
+#ifndef _DB_STL_DBC_H
+#define _DB_STL_DBC_H
+
+#include <set>
+#include <errno.h>
+
+#include "dbstl_common.h"
+#include "dbstl_dbt.h"
+#include "dbstl_exception.h"
+#include "dbstl_container.h"
+#include "dbstl_resource_manager.h"
+
+START_NS(dbstl)
+
+// Forward declarations.
+class db_container;
+class DbCursorBase;
+template<Typename data_dt>
+class RandDbCursor;
+class DbstlMultipleKeyDataIterator;
+class DbstlMultipleRecnoDataIterator;
+using std::set;
+
+/////////////////////////////////////////////////////////////////////
+/////////////////////////////////////////////////////////////////////
+//
+// LazyDupCursor class template definition.
+//
+// This class allows us to make a shallow copy on construction. When the
+// cursor pointer is first dereferenced a deep copy is made.
+//
+// The allowed type for BaseType is DbCursor<> and RandDbCursor<>
+// The expected usage of this class is:
+// 1. Create an iterator in container::begin(), the iterator::pcsr.csr_ptr_
+// points to an object, thus no need to duplicate.
+// 2. The iterator is created with default argument, thus the
+// iterator::pcsr.csr_ptr_ and dup_src_ is NULL, and this iterator is
+// copied using copy constructor for may be many times, but until the
+// cursor is really used, no cursor is duplicated.
+//
+// There is an informing mechanism between an instance of this class and
+// its dup_src_ cursor: when that cursor is about to change state, it will
+// inform all registered LazyDupCursor "listeners" of the change, so that
+// they will duplicate from the cursor before the change, because that
+// is the expected cursor state for the listeners.
+
+template <Typename BaseType>
+class LazyDupCursor
+{
+	// dup_src_ is used by this class internally to duplicate another
+	// cursor and set to csr_ptr_, and it is assigned in the copy
+	// constructor from another LazyDupCursor object's csr_ptr_; csr_ptr_
+	// is the acutual pointer that is used to perform cursor operations.
+	//
+	BaseType *csr_ptr_, *dup_src_;
+	typedef LazyDupCursor<BaseType> self;
+
+public:
+	////////////////////////////////////////////////////////////////////
+	//
+	// Begin public constructors and destructor.
+	//
+	inline LazyDupCursor()
+	{
+		csr_ptr_ = NULL;
+		dup_src_ = NULL;
+	}
+
+	// Used in all iterator types' constructors, dbcptr is created
+	// solely for this object, and the cursor is not yet opened, so we
+	// simply assign it to csr_ptr_.
+	explicit inline LazyDupCursor(BaseType *dbcptr)
+	{
+		csr_ptr_ = dbcptr;
+		// Already have pointer, do not need to duplicate.
+		dup_src_ = NULL;
+	}
+
+	// Do not copy to csr_ptr_, shallow copy from dp2.csr_ptr_.
+	LazyDupCursor(const self& dp2)
+	{
+		csr_ptr_ = NULL;
+		if (dp2.csr_ptr_)
+			dup_src_ = dp2.csr_ptr_;
+		else
+			dup_src_ = dp2.dup_src_;
+		if (dup_src_)
+			dup_src_->add_dupper(this);
+	}
+
+	~LazyDupCursor()
+	{
+		// Not duplicated yet, remove from dup_src_.
+		if (csr_ptr_ == NULL && dup_src_ != NULL)
+			dup_src_->erase_dupper(this);
+		if (csr_ptr_)
+			delete csr_ptr_;// Delete the cursor.
+	}
+
+	////////////////////////////////////////////////////////////////////
+
+	// Deep copy.
+	inline const self& operator=(const self &dp2)
+	{
+		BaseType *dcb;
+
+		dcb = dp2.csr_ptr_ ? dp2.csr_ptr_ : dp2.dup_src_;
+		this->operator=(dcb);
+
+		return dp2;
+	}
+
+	// Deep copy.
+	inline BaseType *operator=(BaseType *dcb)
+	{
+
+		if (csr_ptr_) {
+			// Only dup_src_ will inform this, not csr_ptr_.
+			delete csr_ptr_;
+			csr_ptr_ = NULL;
+		}
+
+		if (dcb)
+			csr_ptr_ = new BaseType(*dcb);
+		if (dup_src_ != NULL) {
+			dup_src_->erase_dupper(this);
+			dup_src_ = NULL;
+		}
+
+		return dcb;
+	}
+
+	void set_cursor(BaseType *dbc)
+	{
+		assert(dbc != NULL);
+		if (csr_ptr_) {
+			// Only dup_src_ will inform this, not csr_ptr_.
+			delete csr_ptr_;
+			csr_ptr_ = NULL;
+		}
+
+		csr_ptr_ = dbc;
+		if (dup_src_ != NULL) {
+			dup_src_->erase_dupper(this);
+			dup_src_ = NULL;
+		}
+	}
+
+	// If dup_src_ is informing this object, pass false parameter.
+	inline BaseType* duplicate(bool erase_dupper = true)
+	{
+		assert(dup_src_ != NULL);
+		if (csr_ptr_) {
+			// Only dup_src_ will inform this, not csr_ptr_.
+			delete csr_ptr_;
+			csr_ptr_ = NULL;
+		}
+		csr_ptr_ = new BaseType(*dup_src_);
+		if (erase_dupper)
+			dup_src_->erase_dupper(this);
+		dup_src_ = NULL;
+		return csr_ptr_;
+	}
+
+	inline BaseType* operator->()
+	{
+		if (csr_ptr_)
+			return csr_ptr_;
+
+		return duplicate();
+	}
+
+	inline operator bool()
+	{
+		return csr_ptr_ != NULL;
+	}
+
+	inline bool operator!()
+	{
+		return !csr_ptr_;
+	}
+
+	inline bool operator==(void *p)
+	{
+		return csr_ptr_ == p;
+	}
+
+	inline BaseType* base_ptr(){
+		if (csr_ptr_)
+			return csr_ptr_;
+		return duplicate();
+	}
+};
+
+
+/////////////////////////////////////////////////////////////////////////
+/////////////////////////////////////////////////////////////////////////
+//
+// DbCursorBase class definition.
+//
+// DbCursorBase is the base class for DbCursor<> class template, this class
+// wraps the Berkeley DB cursor, in order for the ResourceManager to close
+// the Berkeley DB cursor and set the pointer to null. 
+// If we don't set the cursor to NULL, the handle could become valid again,
+// since Berkeley DB recycles handles. DB STL would then try to use the same
+// handle across different instances, which is not supported.
+//
+// In ResourceManager, whenver a cursor is opened, it stores the
+// DbCursorBase* pointer, so that when need to close the cursor, it calls
+// DbCursorBase::close() function.
+//
+class DbCursorBase
+{
+protected:
+	Dbc *csr_;
+	DbTxn *owner_txn_;
+	Db *owner_db_;
+	int csr_status_;
+
+public:
+	enum DbcGetSkipOptions{SKIP_KEY, SKIP_DATA, SKIP_NONE};
+	inline DbTxn *get_owner_txn() const { return owner_txn_;}
+	inline void set_owner_txn(DbTxn *otxn) { owner_txn_ = otxn;}
+
+	inline Db *get_owner_db() const { return owner_db_;}
+	inline void set_owner_db(Db *odb) { owner_db_ = odb;}
+
+	inline Dbc *get_cursor()  const { return csr_;}
+	inline Dbc *&get_cursor_reference() { return csr_;}
+	inline void set_cursor(Dbc*csr1)
+	{
+		if (csr_)
+			ResourceManager::instance()->remove_cursor(this);
+		csr_ = csr1;
+	}
+
+	inline int close()
+	{
+		int ret = 0;
+
+		if (csr_ != NULL && (((DBC *)csr_)->flags & DBC_ACTIVE) != 0) {
+			ret = csr_->close();
+			csr_ = NULL;
+		}
+		return ret;
+	}
+
+	DbCursorBase(){
+		owner_txn_ = NULL;
+		owner_db_ = NULL;
+		csr_ = NULL;
+		csr_status_ = 0;
+	}
+
+	DbCursorBase(const DbCursorBase &csrbase)
+	{
+		this->operator=(csrbase);
+	}
+
+	const DbCursorBase &operator=(const DbCursorBase &csrbase)
+	{
+		owner_txn_ = csrbase.owner_txn_;
+		owner_db_ = csrbase.owner_db_;
+		csr_ = NULL; // Need to call DbCursor<>::dup to duplicate.
+		csr_status_ = 0;
+		return csrbase;
+	}
+
+	virtual ~DbCursorBase()
+	{
+		close();
+	}
+}; // DbCursorBase
+
+////////////////////////////////////////////////////////////////////////
+///////////////////////////////////////////////////////////////////////
+//
+// DbCursor class template definition
+//
+// DbCursor is the connection between Berkeley DB and dbstl container classes
+// it is the wrapper class for Dbc* cursor of Berkeley Db, to be used for
+// iterator classes of Berkeley DB backed STL container classes.
+// Requirement:
+// 1. Deep copy using Dbc->dup.
+// 2. Dbc*cursor management via ResourceManager class.
+// 3. Provide methods to do increment, decrement and advance operations,
+//    advance is only available for random access iterator from DB_RECNO
+//    containers.
+//
+
+template<typename key_dt, typename data_dt>
+class DbCursor : public DbCursorBase{
+protected:
+	// Lazy duplication support: store the LazyDupCursor objects which
+	// will duplicate from this cursor.
+	typedef LazyDupCursor<DbCursor<key_dt, data_dt> > dupper_t;
+	typedef LazyDupCursor<RandDbCursor<data_dt> > dupperr_t;
+	typedef set<LazyDupCursor<DbCursor<key_dt, data_dt> >* > dupset_t;
+	typedef set<LazyDupCursor<RandDbCursor<data_dt> >* > dupsetr_t;
+
+	set<LazyDupCursor<DbCursor<key_dt, data_dt> >* > sduppers1_;
+	set<LazyDupCursor<RandDbCursor<data_dt> >* > sduppers2_;
+
+	// We must use DB_DBT_USERMEM for Dbc::get and Db::get if they are
+	// used in multi-threaded application, so we use key_buf_ and
+	// data_buf_ data members for get operations, and initialize them
+	// to use user memory.
+	Dbt key_buf_, data_buf_;
+
+	// Similar to Berkeley DB C++ API's classes, used to iterate through
+	// bulk retrieved key/data pairs.
+	DbstlMultipleKeyDataIterator *multi_itr_;
+	DbstlMultipleRecnoDataIterator *recno_itr_;
+
+	// Whether to use bulk retrieval. If non-zero, do bulk retrieval,
+	// bulk buffer size is this member, otherwise not bulk read.
+	// By default this member is 0.
+	u_int32_t bulk_retrieval_;
+	// Whether to use DB_RMW flag in Dbc::get, by default false.
+	bool rmw_get_;
+
+	// Whether to poll data from cursor's current position on every
+	// get_current_key/data call.
+	// Note that curr_key_/curr_data_ members are always maintained
+	// to contain current k/d value of the pair pointed to by csr_.
+	// If doing bulk retrieval, this flag is ignored, we will always
+	// read data from bulk buffer.
+	bool directdb_get_;
+
+	// Inform LazyDupCursor objects registered in this object to do
+	// duplication because this cursor is to be changed.
+	// This function should be called in any function of
+	// DbCursor and RandDbCursor whenever the cursor is about to change
+	// state(move/close, etc).
+	inline void inform_duppers()
+	{
+		typename dupset_t::iterator i1;
+		typename dupsetr_t::iterator i2;
+		for (i1 = sduppers1_.begin(); i1 != sduppers1_.end(); i1++)
+			(*i1)->duplicate(false);
+		for (i2 = sduppers2_.begin(); i2 != sduppers2_.end(); i2++)
+			(*i2)->duplicate(false);
+		sduppers1_.clear();
+		sduppers2_.clear();
+	}
+
+public:
+	friend class DataItem;
+
+	// Current key/data pair pointed by "csr_" Dbc*cursor. They are both
+	// maintained on cursor movement. If directdb_get_ is true,
+	// they are both refreshed on every get_current{[_key][_data]} call and 
+	// the retrieved key/data pair is returned to user.
+	DataItem curr_key_;
+	DataItem curr_data_;
+
+	typedef DbCursor<key_dt, data_dt> self;
+
+	// This function is used by all iterators to do equals comparison.
+	// Random iterators will also use it to do less than/greater than
+	// comparisons.
+	// Internally, the page number difference or index difference is
+	// returned, so for btree and hash databases, if two cursors point to
+	// the same key/data pair, we will get 0 returned, meaning they are
+	// equal; if return value is not 0, it means no more than that they
+	// they are not equal. We can't assume any order information between
+	// the two cursors. For recno databases, we use the recno to do less
+	// than and greater than comparison. So we can get a reliable knowledge
+	// of the relative position of two iterators from the return value.
+	int compare(const self *csr2) const{
+		int res, ret;
+
+		BDBOP(((DBC *)csr_)->cmp((DBC *)csr_, (DBC *)csr2->csr_,
+		    &res, 0), ret);
+		return res;
+	}
+
+	////////////////////////////////////////////////////////////////////
+	//
+	// Add and remove cursor change event listeners.
+	//
+	inline void add_dupper(dupper_t *dupper)
+	{
+		sduppers1_.insert(dupper);
+	}
+
+	inline void add_dupper(dupperr_t *dupper)
+	{
+		sduppers2_.insert(dupper);
+	}
+
+	inline void erase_dupper(dupper_t *dup1)
+	{
+		sduppers1_.erase(dup1);
+	}
+
+	inline void erase_dupper(dupperr_t *dup1)
+	{
+		sduppers2_.erase(dup1);
+	}
+
+	////////////////////////////////////////////////////////////////////
+
+public:
+
+	inline bool get_rmw()
+	{
+		return rmw_get_;
+	}
+
+	bool set_rmw(bool rmw, DB_ENV *env = NULL )
+	{
+		u_int32_t flag = 0;
+		DB_ENV *dbenv = NULL;
+		int ret;
+
+		if (env)
+			dbenv = env;
+		else
+			dbenv = ((DBC*)csr_)->dbenv;
+		BDBOP(dbenv->get_open_flags(dbenv, &flag), ret);
+
+		// DB_RMW flag requires locking subsystem started.
+		if (rmw && ((flag & DB_INIT_LOCK) || (flag & DB_INIT_CDB) ||
+		    (flag & DB_INIT_TXN)))
+			rmw_get_ = true;
+		else
+			rmw_get_ = false;
+		return rmw_get_;
+	}
+
+	// Modify bulk buffer size. Bulk read is enabled when creating an
+	// iterator, so users later can only modify the bulk buffer size
+	// to another value, but can't enable/disable bulk read while an
+	// iterator is already alive. 
+	// Returns true if succeeded, false otherwise.
+	inline bool set_bulk_buffer(u_int32_t sz)
+	{
+		if (bulk_retrieval_ && sz) {
+			normalize_bulk_bufsize(sz);
+			bulk_retrieval_ = sz;
+			return true;
+		}
+
+		return false;
+
+	}
+
+	inline u_int32_t get_bulk_bufsize()
+	{
+		return bulk_retrieval_;
+	}
+
+	inline void enlarge_dbt(Dbt &d, u_int32_t sz)
+	{
+		void *p;
+
+		p = DbstlReAlloc(d.get_data(), sz);
+		dbstl_assert(p != NULL);
+		d.set_ulen(sz);
+		d.set_data(p);
+		d.set_size(sz);
+	}
+	// Move forward or backward, often by 1 key/data pair, we can use
+	// different flags for Dbc::get function. Then update the key/data
+	// pair and csr_status_ members.
+	//
+	int increment(int flag)
+	{
+		int ret = 0;
+		Dbt &k = key_buf_, &d = data_buf_;
+		u_int32_t sz, getflags = 0, bulk_bufsz;
+
+		if (csr_ == NULL)
+			return INVALID_ITERATOR_CURSOR;
+		curr_key_.reset();
+		curr_data_.reset();
+		inform_duppers();
+
+		// Berkeley DB cursor flags are not bitwise set, so we can't
+		// use bit operations here.
+		//
+		if (this->bulk_retrieval_ != 0)
+			switch (flag) {
+			case DB_PREV:
+			case DB_PREV_DUP:
+			case DB_PREV_NODUP:
+			case DB_LAST:
+			case DB_JOIN_ITEM:
+			case DB_GET_RECNO:
+			case DB_SET_RECNO: 
+				break;
+			default:
+				getflags |= DB_MULTIPLE_KEY;
+				if (data_buf_.get_ulen() != bulk_retrieval_)
+					enlarge_dbt(data_buf_, bulk_retrieval_);
+				break;
+			}
+
+		if (this->rmw_get_)
+			getflags |= DB_RMW;
+
+		// Do not use BDBOP or BDBOP2 here because it is likely
+		// that an iteration will step onto end() position.
+retry:		ret = csr_->get(&k, &d, flag | getflags);
+		if (ret == 0) {
+			if (bulk_retrieval_ && (getflags & DB_MULTIPLE_KEY)) {
+				// A new retrieval, so both multi_itr_ and
+				// recno_itr_ must be NULL.
+				if (((DBC*)csr_)->dbtype == DB_RECNO) {
+					if (recno_itr_) {
+						delete recno_itr_;
+						recno_itr_ = NULL;
+					}
+					recno_itr_ =
+				    new DbstlMultipleRecnoDataIterator(d);
+				} else {
+					if (multi_itr_) {
+						delete multi_itr_;
+						multi_itr_ = NULL;
+					}
+					multi_itr_ = new
+					    DbstlMultipleKeyDataIterator(d);
+				}
+			} else {
+				// Non bulk retrieval succeeded.
+				curr_key_.set_dbt(k, false);
+				curr_data_.set_dbt(d, false);
+				limit_buf_size_after_use();
+			}
+		} else if (ret == DB_BUFFER_SMALL) {
+			// Either the key or data DBTs might trigger a
+			// DB_KEYSMALL return. Only enlarge the DBT if it 
+			// is actually too small. 
+			if (((sz = d.get_size()) > 0) && (sz > d.get_ulen()))
+				enlarge_dbt(d, sz);
+
+			if (((sz = k.get_size()) > 0) && (sz > k.get_ulen()))
+				enlarge_dbt(k, sz);
+
+			goto retry;
+		} else {
+			if (ret == DB_NOTFOUND) {
+				ret = INVALID_ITERATOR_POSITION;
+				this->curr_key_.reset();
+				this->curr_data_.reset();
+			} else if (bulk_retrieval_ &&
+			    (getflags & DB_MULTIPLE_KEY)){
+				BDBOP(((DBC*)csr_)->dbp->
+				    get_pagesize(((DBC*)csr_)->
+				    dbp, &bulk_bufsz), ret);
+				if (bulk_bufsz > d.get_ulen()) {// buf size error
+					normalize_bulk_bufsize(bulk_bufsz);
+					bulk_retrieval_ = bulk_bufsz;
+					enlarge_dbt(d, bulk_bufsz);
+					goto retry;
+				} else
+					throw_bdb_exception(
+					    "DbCursor<>::increment", ret);
+			} else
+				throw_bdb_exception(
+				    "DbCursor<>::increment", ret);
+		}
+
+		csr_status_ = ret;
+		return ret;
+	}
+
+	// After each use of key_buf_ and data_buf_, limit their buffer size to
+	// a reasonable size so that they don't waste a big memory space.
+	inline void limit_buf_size_after_use() 
+	{
+		if (bulk_retrieval_)
+			// Bulk buffer has to be huge, so don't check it.
+			return;
+
+		if (key_buf_.get_ulen() > DBSTL_MAX_KEY_BUF_LEN) {
+			key_buf_.set_data(DbstlReAlloc(key_buf_.get_data(),
+			    DBSTL_MAX_KEY_BUF_LEN));
+			key_buf_.set_ulen(DBSTL_MAX_KEY_BUF_LEN);
+		}
+		if (data_buf_.get_ulen() > DBSTL_MAX_DATA_BUF_LEN) {
+			data_buf_.set_data(DbstlReAlloc(data_buf_.get_data(),
+			    DBSTL_MAX_DATA_BUF_LEN));
+			data_buf_.set_ulen(DBSTL_MAX_DATA_BUF_LEN);
+		}
+	}
+
+	// Duplicate this object's cursor and set it to dbc1.
+	//
+	inline int dup(DbCursor<key_dt, data_dt>& dbc1) const
+	{
+		Dbc* pcsr = 0;
+		int ret;
+
+		if (csr_ != 0 && csr_->dup(&pcsr, DB_POSITION) == 0) {
+			dbc1.set_cursor(pcsr);
+			dbc1.set_owner_db(this->get_owner_db());
+			dbc1.set_owner_txn(this->get_owner_txn());
+			ResourceManager::instance()->add_cursor(
+			    this->get_owner_db(), &dbc1);
+			ret = 0;
+		} else
+			ret = ITERATOR_DUP_ERROR;
+
+		return ret;
+	}
+
+public:
+	// Open a cursor, do not move it, it is at an invalid position.
+	// All cursors should be opened using this method.
+	//
+	inline int open(db_container *pdbc, int flags)
+	{
+		int ret;
+
+		Db *pdb = pdbc->get_db_handle();
+		if (pdb == NULL)
+			return 0;
+		if (csr_) // Close before open.
+			return 0;
+		ret = ResourceManager::instance()->
+		    open_cursor(this, pdb, flags);
+		set_rmw(rmw_get_);
+		this->csr_status_ = ret;
+		return ret;
+	}
+
+	// Move Berkeley DB cursor to specified key k, by default use DB_SET,
+	// but DB_SET_RANGE can and may also be used.
+	//
+	int move_to(const key_dt&k, u_int32_t flag = DB_SET)
+	{
+		Dbt &d1 = data_buf_;
+		int ret;
+		u_int32_t sz;
+		DataItem k1(k, true);
+
+		if (csr_ == NULL)
+			return INVALID_ITERATOR_CURSOR;
+
+		curr_key_.reset();
+		curr_data_.reset();
+		inform_duppers();
+
+		// It is likely that k is not in db, causing get(DB_SET) to
+		// fail, we should not throw an exception because of this.
+		//
+		if (rmw_get_)
+			flag |= DB_RMW;
+retry:		ret = csr_->get(&k1.get_dbt(), &d1, flag);
+		if (ret == 0) {
+			curr_key_ = k1;
+			curr_data_.set_dbt(d1, false);
+			limit_buf_size_after_use();
+		} else if (ret == DB_BUFFER_SMALL) {
+			sz = d1.get_size();
+			assert(sz > 0);
+			enlarge_dbt(d1, sz);
+			goto retry;
+		} else {
+			if (ret == DB_NOTFOUND) {
+				ret = INVALID_ITERATOR_POSITION;
+				// Invalidate current values because it is
+				// at an invalid position.
+				this->curr_key_.reset();
+				this->curr_data_.reset();
+			} else
+				throw_bdb_exception("DbCursor<>::move_to", ret);
+		}
+
+		csr_status_ = ret;
+		return ret;
+	}
+
+	// Returns the number of keys equal to the current one.
+	inline size_t count()
+	{
+		int ret;
+		db_recno_t cnt;
+
+		BDBOP2(csr_->count(&cnt, 0), ret, close());
+		return (size_t)cnt;
+	}
+
+	int insert(const key_dt&k, const data_dt& d, int pos = DB_BEFORE)
+	{
+		// !!!XXX:
+		//         We do a deep copy of the input data into a local
+		//         variable. Apparently not doing so causes issues
+		//         when using gcc. Even though the put completes prior
+		//         to returning from this function call.
+		//         It would be best to avoid this additional copy.
+		int ret;
+		// (k, d) pair may be a temporary pair, so we must copy them.
+		DataItem k1(k, false), d1(d, false);
+
+		inform_duppers();
+		if (pos == DB_AFTER) {
+			ret = this->csr_->put(&k1.get_dbt(), &d1.get_dbt(),
+			    pos);
+			// May be using this flag for an empty database,
+			// because begin() an iterator of an empty db_vector
+			// equals its end() iterator, so use DB_KEYLAST to
+			// retry.
+			//
+			if (ret == EINVAL || ret == 0)
+				return ret;
+			else if (ret)
+				throw_bdb_exception("DbCursor<>::insert", ret);
+		}
+		if (pos == DB_NODUPDATA)
+			BDBOP3(this->csr_->put(&k1.get_dbt(), &d1.get_dbt(),
+			    pos), ret, DB_KEYEXIST, close());
+		else
+			BDBOP2(this->csr_->put(&k1.get_dbt(), &d1.get_dbt(),
+			    pos), ret, close());
+		this->csr_status_ = ret;
+		if (ret == 0) {
+			curr_key_ = k1;
+			curr_data_ = d1;
+		}
+		// This cursor points to the new key/data pair now.
+		return ret;
+	}
+
+	// Replace current cursor-pointed data item with d.
+	inline int replace(const data_dt& d)
+	{
+		Dbt k1;
+		int ret;
+		// !!!XXX:
+		//         We do a deep copy of the input data into a local
+		//         variable. Apparently not doing so causes issues
+		//         when using gcc. Even though the put completes prior
+		//         to returning from this function call.
+		//         It would be best to avoid this additional copy.
+		// d may be a temporary object, so we must copy it.
+		DataItem d1(d, false);
+
+		
+		BDBOP2(this->csr_->put(&k1, &d1.get_dbt(), DB_CURRENT),
+		    ret, close());
+		curr_data_ = d1; // Update current data.
+		
+		this->csr_status_ = ret;
+		return ret;
+	}
+
+	// Remove old key and insert new key-psuodo_data. First insert then
+	// move to old key and remove it so that the cursor remains at the
+	// old key's position, according to DB documentation.
+	// But from practice I can see
+	// the cursor after delete seems not at old position because a for
+	// loop iteration exits prematurelly, not all elements are passed.
+	//
+	inline int replace_key(const key_dt&k)
+	{
+		data_dt d;
+		key_dt k0;
+		int ret;
+
+		this->get_current_key_data(k0, d);
+		if (k0 == k)
+			return 0;
+
+		DbCursor<key_dt, data_dt> csr2;
+		this->dup(csr2);
+		// Delete current, then insert new key/data pair.
+		ret = csr2.del(); 
+		ret = csr2.insert(k, d, DB_KEYLAST);
+		this->csr_status_ = ret;
+		
+		// Now this->csr_ is sitting on an invalid position, its 
+		// iterator is invalidated. Must first move it to the next
+		// position before using it.
+		return ret;
+	}
+
+	inline int del()
+	{
+		int ret;
+
+		inform_duppers();
+		BDBOP2(csr_->del(0), ret, close());
+
+		// By default pos.csr_ will stay at where it was after delete,
+		// which now is an invalid position. So we need to move to
+		// next to conform to stl specifications, but we don't move it
+		// here, iterator::erase should move the iterator itself 
+		// forward.
+		//
+		this->csr_status_ = ret;
+		return ret;
+	}
+
+	// Make sure the bulk buffer is large enough, and a multiple of 1KB. 
+	// This function may be called prior to cursor initialization, it is 
+	// not possible to verify that the buffer size is a multiple of the 
+	// page size here.
+	u_int32_t normalize_bulk_bufsize(u_int32_t &bulksz)
+	{
+		if (bulksz == 0)
+			return 0;
+
+		while (bulksz < 16 * sizeof(data_dt))
+			bulksz *= 2;
+
+		bulksz = bulksz + 1024 - bulksz % 1024;
+
+		return bulksz;
+	}
+
+	////////////////////////////////////////////////////////////////////
+	//
+	// Begin public constructors and destructor.
+	//
+	explicit DbCursor(u_int32_t b_bulk_retrieval = 0, bool brmw1 = false,
+	    bool directdbget = true) : DbCursorBase(),
+	    curr_key_(sizeof(key_dt)), curr_data_(sizeof(data_dt))
+	{
+		u_int32_t bulksz = sizeof(data_dt); // non-bulk
+		rmw_get_ = brmw1;
+		this->bulk_retrieval_ = 
+		    normalize_bulk_bufsize(b_bulk_retrieval);
+		recno_itr_ = NULL;
+		multi_itr_ = NULL;
+
+		if (bulk_retrieval_) {
+			if (bulksz <= bulk_retrieval_)
+				bulksz = bulk_retrieval_;
+			else {
+				normalize_bulk_bufsize(bulksz);
+				bulk_retrieval_ = bulksz;
+			}
+		}
+		key_buf_.set_data(DbstlMalloc(sizeof(key_dt)));
+		key_buf_.set_ulen(sizeof(key_dt));
+		key_buf_.set_flags(DB_DBT_USERMEM);
+		data_buf_.set_data(DbstlMalloc(bulksz));
+		data_buf_.set_ulen(bulksz);
+		data_buf_.set_flags(DB_DBT_USERMEM);
+		directdb_get_ = directdbget;
+	}
+
+	// Copy constructor, duplicate cursor here.
+	DbCursor(const DbCursor<key_dt, data_dt>& dbc) :
+	    DbCursorBase(dbc),
+	    curr_key_(dbc.curr_key_), curr_data_(dbc.curr_data_)
+	{
+		void *pk, *pd;
+
+		dbc.dup(*this);
+		csr_status_ = dbc.csr_status_;
+		if (csr_ || dbc.csr_)
+			this->rmw_get_ = set_rmw(dbc.rmw_get_,
+			    ((DBC*)dbc.csr_)->dbenv);
+		else
+			rmw_get_ = dbc.rmw_get_;
+
+		bulk_retrieval_ = dbc.bulk_retrieval_;
+
+		// Now we have to copy key_buf_ and data_buf_ to support
+		// multiple retrieval.
+		key_buf_.set_data(pk = DbstlMalloc(dbc.key_buf_.get_ulen()));
+		key_buf_.set_ulen(dbc.key_buf_.get_ulen());
+		key_buf_.set_size(dbc.key_buf_.get_size());
+		key_buf_.set_flags(DB_DBT_USERMEM);
+		memcpy(pk, dbc.key_buf_.get_data(), key_buf_.get_ulen());
+
+		data_buf_.set_data(pd = DbstlMalloc(dbc.data_buf_.get_ulen()));
+		data_buf_.set_ulen(dbc.data_buf_.get_ulen());
+		data_buf_.set_size(dbc.data_buf_.get_size());
+		data_buf_.set_flags(DB_DBT_USERMEM);
+		memcpy(pd, dbc.data_buf_.get_data(), data_buf_.get_ulen());
+		if (dbc.recno_itr_) {
+			recno_itr_ = new DbstlMultipleRecnoDataIterator(
+			    data_buf_);
+			recno_itr_->set_pointer(dbc.recno_itr_->get_pointer());
+		} else
+			recno_itr_ = NULL;
+		if (dbc.multi_itr_) {
+			multi_itr_ = new DbstlMultipleKeyDataIterator(
+			    data_buf_);
+			multi_itr_->set_pointer(dbc.multi_itr_->get_pointer());
+
+		} else
+			multi_itr_ = NULL;
+
+		directdb_get_ = dbc.directdb_get_;
+
+		// Do not copy sduppers, they are private to each DbCursor<>
+		// object.
+	}
+
+	virtual ~DbCursor()
+	{
+		close(); // Call close() ahead of freeing following buffers.
+		free(key_buf_.get_data());
+		free(data_buf_.get_data());
+		if (multi_itr_)
+			delete multi_itr_;
+		if (recno_itr_)
+			delete recno_itr_;
+	}
+
+	////////////////////////////////////////////////////////////////////
+
+	const DbCursor<key_dt, data_dt>& operator=
+	    (const DbCursor<key_dt, data_dt>& dbc)
+	{
+		void *pk;
+		u_int32_t ulen;
+
+		DbCursorBase::operator =(dbc);
+		dbc.dup(*this);
+		curr_key_ = dbc.curr_key_;
+		curr_data_ = dbc.curr_data_;
+		rmw_get_ = dbc.rmw_get_;
+		this->bulk_retrieval_ = dbc.bulk_retrieval_;
+		this->directdb_get_ = dbc.directdb_get_;
+		// Now we have to copy key_buf_ and data_buf_ to support
+		// bulk retrieval.
+		key_buf_.set_data(pk = DbstlReAlloc(key_buf_.get_data(),
+		    ulen = dbc.key_buf_.get_ulen()));
+		key_buf_.set_ulen(ulen);
+		key_buf_.set_size(dbc.key_buf_.get_size());
+		key_buf_.set_flags(DB_DBT_USERMEM);
+		memcpy(pk, dbc.key_buf_.get_data(), ulen);
+
+		data_buf_.set_data(pk = DbstlReAlloc(key_buf_.get_data(),
+		    ulen = dbc.key_buf_.get_ulen()));
+		data_buf_.set_ulen(ulen);
+		data_buf_.set_size(dbc.data_buf_.get_size());
+		data_buf_.set_flags(DB_DBT_USERMEM);
+		memcpy(pk, dbc.key_buf_.get_data(), ulen);
+
+		if (dbc.recno_itr_) {
+			if (recno_itr_) {
+				delete recno_itr_;
+				recno_itr_ = NULL;
+			}
+			recno_itr_ = new DbstlMultipleRecnoDataIterator(
+			    data_buf_);
+			recno_itr_->set_pointer(dbc.recno_itr_->get_pointer());
+		} else if (recno_itr_) {
+			delete recno_itr_;
+			recno_itr_ = NULL;
+		}
+
+		if (dbc.multi_itr_) {
+			if (multi_itr_) {
+				delete multi_itr_;
+				multi_itr_ = NULL;
+			}
+			multi_itr_ = new DbstlMultipleKeyDataIterator(
+			    data_buf_);
+			multi_itr_->set_pointer(dbc.multi_itr_->get_pointer());
+
+		} else if (multi_itr_) {
+			delete multi_itr_;
+			multi_itr_ = NULL;
+		}
+
+		return dbc;
+		// Do not copy sduppers, they are private to each DbCursor<>
+		// object.
+
+	}
+
+	// Move Dbc*cursor to next position. If doing bulk read, read from
+	// the bulk buffer. If bulk buffer exhausted, do another bulk read
+	// from database, and then read from the bulk buffer. Quit if no
+	// more data in database.
+	//
+	int next(int flag = DB_NEXT)
+	{
+		Dbt k, d;
+		db_recno_t recno;
+		int ret;
+
+retry:		if (bulk_retrieval_) {
+			if (multi_itr_) {
+				if (multi_itr_->next(k, d)) {
+					curr_key_.set_dbt(k, false);
+					curr_data_.set_dbt(d, false);
+					return 0;
+				} else {
+					delete multi_itr_;
+					multi_itr_ = NULL;
+				}
+			}
+			if (recno_itr_) {
+				if (recno_itr_->next(recno, d)) {
+					curr_key_.set_dbt(k, false);
+					curr_data_.set_dbt(d, false);
+					return 0;
+				} else {
+					delete recno_itr_;
+					recno_itr_ = NULL;
+				}
+			}
+		}
+		ret = increment(flag);
+		if (bulk_retrieval_ && ret == 0)
+			goto retry;
+		return ret;
+	}
+
+	inline int prev(int flag = DB_PREV)
+	{
+		return increment(flag);
+	}
+
+	// Move Dbc*cursor to first element. If doing bulk read, read data
+	// from bulk buffer.
+	int first()
+	{
+		Dbt k, d;
+		db_recno_t recno;
+		int ret;
+
+		ret = increment(DB_FIRST);
+		if (bulk_retrieval_) {
+			if (multi_itr_) {
+				if (multi_itr_->next(k, d)) {
+					curr_key_.set_dbt(k, false);
+					curr_data_.set_dbt(d, false);
+					return 0;
+				} else {
+					delete multi_itr_;
+					multi_itr_ = NULL;
+				}
+			}
+			if (recno_itr_) {
+				if (recno_itr_->next(recno, d)) {
+					curr_key_.set_dbt(k, false);
+					curr_data_.set_dbt(d, false);
+					return 0;
+				} else {
+					delete recno_itr_;
+					recno_itr_ = NULL;
+				}
+			}
+		}
+
+		return ret;
+	}
+
+	inline int last()
+	{
+		return increment(DB_LAST);
+	}
+
+	// Get current key/data pair, shallow copy. Return 0 on success,
+	// -1 if no data.
+	inline int get_current_key_data(key_dt&k, data_dt&d)
+	{
+		if (directdb_get_)
+			update_current_key_data_from_db(
+			    DbCursorBase::SKIP_NONE);
+		if (curr_key_.get_data(k) == 0 && curr_data_.get_data(d) == 0)
+			return 0;
+		else 
+			return INVALID_KEY_DATA;
+	}
+
+	// Get current data, shallow copy. Return 0 on success, -1 if no data.
+	inline int get_current_data(data_dt&d)
+	{
+		if (directdb_get_)
+			update_current_key_data_from_db(DbCursorBase::SKIP_KEY);
+		if (curr_data_.get_data(d) == 0)
+			return 0;
+		else 
+			return INVALID_KEY_DATA;
+	}
+
+	// Get current key, shallow copy. Return 0 on success, -1 if no data.
+	inline int get_current_key(key_dt&k)
+	{
+		if (directdb_get_)
+			update_current_key_data_from_db(
+			    DbCursorBase::SKIP_DATA);
+		if (curr_key_.get_data(k) == 0)
+			return 0;
+		else 
+			return INVALID_KEY_DATA;
+	}
+
+	inline void close()
+	{
+		if (csr_) {
+			inform_duppers();
+			ResourceManager::instance()->remove_cursor(this);
+		}
+		csr_ = NULL;
+	}
+
+	// Parameter skipkd specifies skip retrieving key or data:
+	// If 0, don't skip, retrieve both;
+	// If 1, skip retrieving key;
+	// If 2, skip retrieving data.
+	// Do not poll from db again if doing bulk retrieval.
+	void update_current_key_data_from_db(DbcGetSkipOptions skipkd) {
+		int ret;
+		u_int32_t sz, sz1, kflags = DB_DBT_USERMEM,
+		    dflags = DB_DBT_USERMEM;
+		// Do not poll from db again if doing bulk retrieval.
+		if (this->bulk_retrieval_)
+			return;
+		if (this->csr_status_ != 0) {
+			curr_key_.reset();
+			curr_data_.reset();
+			return;
+		}
+		
+		// We will modify flags if skip key or data, so cache old
+		// value and set it after get calls.
+		if (skipkd != DbCursorBase::SKIP_NONE) {
+			kflags = key_buf_.get_flags();
+			dflags = data_buf_.get_flags();
+		}
+		if (skipkd == DbCursorBase::SKIP_KEY) {
+			key_buf_.set_dlen(0);
+			key_buf_.set_flags(DB_DBT_PARTIAL | DB_DBT_USERMEM);
+		}
+
+		if (skipkd == DbCursorBase::SKIP_DATA) {
+			data_buf_.set_dlen(0);
+			data_buf_.set_flags(DB_DBT_PARTIAL | DB_DBT_USERMEM);
+		}
+retry:		ret = csr_->get(&key_buf_, &data_buf_, DB_CURRENT);
+		if (ret == 0) {
+			if (skipkd != DbCursorBase::SKIP_KEY)
+				curr_key_ = key_buf_;
+			if (skipkd != DbCursorBase::SKIP_DATA)
+				curr_data_ = data_buf_;
+			limit_buf_size_after_use();
+		} else if (ret == DB_BUFFER_SMALL) {
+			if ((sz = key_buf_.get_size()) > 0)
+				enlarge_dbt(key_buf_, sz);
+			if ((sz1 = data_buf_.get_size()) > 0) 
+				enlarge_dbt(data_buf_, sz1);
+			if (sz == 0 && sz1 == 0)
+				THROW0(InvalidDbtException);
+			goto retry;
+		} else {
+			if (skipkd != DbCursorBase::SKIP_NONE) {
+				key_buf_.set_flags(kflags);
+				data_buf_.set_flags(dflags);
+			}
+			throw_bdb_exception(
+			"DbCursor<>::update_current_key_data_from_db", ret);
+		}
+
+		if (skipkd != DbCursorBase::SKIP_NONE) {
+			key_buf_.set_flags(kflags);
+			data_buf_.set_flags(dflags);
+		}
+	}
+}; // DbCursor<>
+
+////////////////////////////////////////////////////////////////////////
+////////////////////////////////////////////////////////////////////////
+//
+// RandDbCursor class template definition
+//
+// RandDbCursor is a random accessible cursor wrapper for use by
+// db_vector_iterator, it derives from DbCursor<> class. It has a fixed key
+// data type, which is index_type.
+//
+typedef db_recno_t index_type;
+template<Typename data_dt>
+class RandDbCursor : public DbCursor<index_type, data_dt>
+{
+protected:
+	friend class DataItem;
+	typedef ssize_t difference_type;
+public:
+	typedef RandDbCursor<data_dt> self;
+	typedef DbCursor<index_type, data_dt> base;
+
+	// Return current csr_ pointed element's index in recno database
+	// (i.e. the index starting from 1). csr_ must be open and
+	// point to an existing key/data pair.
+	//
+	inline index_type get_current_index() const
+	{
+		index_type ndx;
+
+		if (this->directdb_get_)
+			((self *)this)->update_current_key_data_from_db(
+			    DbCursorBase::SKIP_DATA);
+		this->curr_key_.get_data(ndx);
+		return ndx;
+	}
+
+	inline int compare(const self *csr2) const{
+		index_type i1, i2;
+
+		i1 = this->get_current_index();
+		i2 = csr2->get_current_index();
+		return i1 - i2;
+	}
+
+	// Insert data d before/after current position.
+	int insert(const data_dt& d, int pos = DB_BEFORE){
+		int k = 1, ret;
+		//data_dt dta;
+
+		// Inserting into empty db, must set key to 1.
+		if (pos == DB_KEYLAST)
+			k = 1;
+
+		ret = base::insert(k, d, pos);
+
+		// Inserting into a empty db using begin() itr, so flag is
+		// DB_AFTER and surely failed, so change to use DB_KEYLAST
+		// and try again.
+		if (ret == EINVAL) {
+			k = 1;
+			pos = DB_KEYLAST;
+			ret = base::insert(k, d, pos);
+		}
+		this->csr_status_ = ret;
+		return ret;
+	}
+
+	/*
+	 * Move the cursor n positions, if reaches the beginning or end,
+	 * returns DB_NOTFOUND.
+	 */
+	int advance(difference_type n)
+	{
+		int ret = 0;
+		index_type indx;
+		u_int32_t sz, flags = 0;
+
+		indx = this->get_current_index();
+		if (n == 0)
+			return 0;
+
+		index_type i = (index_type)n;
+		indx += i;
+
+		if (n < 0 && indx < 1) { // Index in recno db starts from 1.
+
+			ret = INVALID_ITERATOR_POSITION;
+			return ret;
+		}
+		this->inform_duppers();
+
+		// Do a search to determine whether new position is valid.
+		Dbt k, &d = this->data_buf_;
+
+		
+		k.set_data(&indx);
+		k.set_size(sizeof(indx));
+		if (this->rmw_get_)
+			flags |= DB_RMW;
+
+retry:		if (this->csr_ && 
+		    ((ret = this->csr_->get(&k, &d, DB_SET)) == DB_NOTFOUND)) {
+			this->csr_status_ = ret = INVALID_ITERATOR_POSITION;
+			this->curr_key_.reset();
+			this->curr_data_.reset();
+		} else if (ret == DB_BUFFER_SMALL) {
+			sz = d.get_size();
+			assert(sz > 0);
+			this->enlarge_dbt(d, sz);
+			goto retry;
+		} else if (ret == 0) {
+			this->curr_key_.set_dbt(k, false);
+			this->curr_data_.set_dbt(d, false);
+			this->limit_buf_size_after_use();
+		} else
+			throw_bdb_exception("RandDbCursor<>::advance", ret);
+		this->csr_status_ = ret;
+		return ret;
+	}
+
+	// Return the last index of recno db (index starting from 1),
+	// it will also move the underlying cursor to last key/data pair.
+	//
+	inline index_type last_index()
+	{
+		int ret;
+
+		ret = this->last();
+		if (ret)
+			return 0;// Invalid position.
+		else
+			return get_current_index();
+	}
+
+	explicit RandDbCursor(u_int32_t b_bulk_retrieval = 0,
+	    bool b_rmw1 = false, bool directdbget = true)
+	    : base(b_bulk_retrieval, b_rmw1, directdbget)
+	{
+	}
+
+	RandDbCursor(const RandDbCursor<data_dt>& rdbc) : base(rdbc)
+	{
+	}
+
+	explicit RandDbCursor(Dbc* csr1, int posidx = 0) : base(csr1)
+	{
+	}
+
+	virtual ~RandDbCursor()
+	{
+	}
+
+}; // RandDbCursor<>
+
+END_NS //ns dbstl
+
+#endif // !_DB_STL_DBC_H
diff --git a/stl/dbstl_dbt.h b/stl/dbstl_dbt.h
new file mode 100644
index 0000000..22d1042
--- /dev/null
+++ b/stl/dbstl_dbt.h
@@ -0,0 +1,803 @@
+/*-
+ * See the file LICENSE for redistribution information.
+ *
+ * Copyright (c) 2009 Oracle.  All rights reserved.
+ *
+ * $Id$
+ */
+
+#ifndef _DB_STL_DBT_H
+#define _DB_STL_DBT_H
+
+#include <assert.h>
+#include <string>
+
+#include "dbstl_common.h"
+#include "dbstl_exception.h"
+#include "dbstl_utility.h"
+
+//////////////////////////////////////////////////////////////////////////
+//////////////////////////////////////////////////////////////////////////
+//
+// DataItem class template definition
+//
+// 1. DataItem is a Dbt wrapper, it provides both typed data to/from memory
+// chunk mapping as well as iostream support. Note that iostream functionality
+// is not yet implemented.
+// 2. DataItem is used inside dbstl to provide consistent Dbt object memory
+// management.
+// 3. DataItem is not only capable of mapping fixed size objects, but also
+// varying length objects and objects not located in a consecutive chunk of
+// memory, with the condition that user configures the required methods in
+// DbstlElemTraits.
+// 4. DataItem can not be a class template because inside it, the "member
+// function template override" support is needed.
+//
+START_NS(dbstl)
+
+using std::string;
+#ifdef HAVE_WSTRING
+using std::wstring;
+#endif
+
+class DataItem
+{
+private:
+	typedef DataItem self;
+
+	////////////////////////////////////////////////////////////////////
+	////////////////////////////////////////////////////////////////////
+	//
+	// DataItem memory management
+	//
+	// The dbt_ member is the current dbt, data is stored in the dbt's 
+	// referenced memory, it may
+	// deep copy from constructor and from other Dbt, depending on
+	// the constructors "onstack" parameter --- if true, this object
+	// is only used as a stack object inside a function,
+	// so do shallow copy; otherwise do deep copy.
+	// There is always a DB_DBT_USERMEM flag set to the dbt,
+	// its ulen data member stores the length of referenced memory,
+	// its size data member stores the actual size of data;
+	// If onstack is true, its dlen is INVALID_DLEN, and freemem()
+	// will not free such memory because this object only reference
+	// other object's memory, its the referenced object's responsibility
+	// to free their memory.
+	//
+	// A DataItem object is not used everywhere, so it is impossible for
+	// such an object to have two kinds of usages as above at the same
+	// time, so we are safe doing so.
+	Dbt dbt_;
+
+	// Free dbt_'s referenced memory if that memory is allocated in heap
+	// and owned by dbt_.
+	inline void freemem()
+	{
+		void *buf = dbt_.get_data();
+
+		if (buf != NULL && (dbt_.get_flags() & DB_DBT_USERMEM) != 0
+		    && dbt_.get_dlen() != INVALID_DLEN)
+			free(buf);
+		memset(&dbt_, 0, sizeof(dbt_));
+	}
+
+public:
+
+	// Deep copy, because dbt2.data pointed memory may be short lived.
+	inline void set_dbt(const DbstlDbt&dbt2, bool onstack)
+	{
+		void *buf;
+		u_int32_t s1, s2;
+		DBT *pdbt2, *pdbt;
+	       
+		pdbt2 = (DBT *)&dbt2;
+		pdbt = (DBT *)&dbt_;
+
+		if (!onstack) {
+			buf = pdbt->data;
+			s1 = pdbt->ulen;
+			s2 = pdbt2->size;
+			if(s2 > s1) {
+				buf = DbstlReAlloc(buf, s2);
+				pdbt->size = s2;
+				pdbt->data = buf;
+				pdbt->ulen = s2;
+				pdbt->flags |= DB_DBT_USERMEM;
+			} else
+				pdbt->size = s2;
+			memcpy(buf, pdbt2->data, s2);
+		} else {
+			freemem();
+			dbt_ = (const Dbt)dbt2;
+			pdbt->dlen = (INVALID_DLEN);
+		}
+	}
+
+	// Deep copy, because dbt2.data pointed memory may be short lived.
+	inline void set_dbt(const Dbt&dbt2, bool onstack)
+	{
+		void *buf;
+		u_int32_t s1, s2;
+		DBT *pdbt2, *pdbt;
+	       
+		pdbt2 = (DBT *)&dbt2;
+		pdbt = (DBT *)&dbt_;
+
+		if (!onstack) {
+			buf = pdbt->data;
+			s1 = pdbt->ulen;
+			s2 = pdbt2->size;
+			if(s2 > s1) {
+				buf = DbstlReAlloc(buf, s2);
+				pdbt->size = s2;
+				pdbt->data = buf;
+				pdbt->ulen = s2;
+				pdbt->flags |= DB_DBT_USERMEM;
+			} else
+				pdbt->size = s2;
+			memcpy(buf, pdbt2->data, s2);
+		} else {
+			freemem();
+			dbt_ = dbt2;
+			pdbt->dlen = (INVALID_DLEN);
+		}
+	}
+
+	inline void set_dbt(const DBT&dbt2, bool onstack)
+	{
+		void *buf;
+		u_int32_t s1, s2;
+		DBT *pdbt = (DBT *)&dbt_;
+
+		if (!onstack) {
+			buf = pdbt->data;
+			s1 = pdbt->ulen;
+			s2 = dbt2.size;
+			if(s2 > s1) {
+				buf = DbstlReAlloc(buf, s2);
+				pdbt->size = s2;
+				pdbt->data = buf;
+				pdbt->ulen = s2;
+				pdbt->flags |= DB_DBT_USERMEM;
+			} else
+				pdbt->size = s2;
+			memcpy(buf, dbt2.data, s2);
+		} else {
+			freemem();
+			// The following is right because Dbt derives from
+			// DBT with no extra members or any virtual functions.
+			memcpy(&dbt_, &dbt2, sizeof(dbt2));
+			pdbt->dlen = INVALID_DLEN;
+		}
+	}
+
+	// Return to the initial state.
+	inline void reset()
+	{
+		void *buf = dbt_.get_data();
+		if (buf) {
+			memset(buf, 0, dbt_.get_ulen());
+			dbt_.set_size(0);
+		}
+	}
+
+	inline Dbt& get_dbt()
+	{
+		return dbt_;
+	}
+
+	// Return data of this object. If no data return -1, if it has data
+	// return 0.
+	//
+	// !!!XXX Note that the type parameter T can only be in this function
+	// because "template type parameter overload" applies only to a
+	// functions template argument list, rather than that of classes.
+	// If you put the "template<Typename T>" to this class's declaration,
+	// making it a class template, then when T is any of Dbt, DBT, or
+	// DataItem<T>, there will be two copies of this function. One will be
+	// this function's instantiated version, the other one is one of the
+	// three functions defined below.
+	//
+	template <Typename T>
+	inline int get_data(T& data) const
+	{
+		int ret;
+		typedef DbstlElemTraits<T> EM;
+		typename EM::ElemRstoreFunct restore;
+		void *pdata = NULL;
+
+		if ((pdata = dbt_.get_data()) != NULL) {
+			if ((restore = EM::instance()->
+			    get_restore_function()) != NULL)
+				restore(data, pdata);
+			else
+				data = *((T*)pdata);
+			ret = 0;
+		} else
+			ret = -1;
+		return ret;
+	}
+
+	////////////////////////////////////////////////////////////////////
+	//
+	// Begin functions supporting direct naked string storage.
+	//
+	// Always store the data, rather than the container object.
+	//
+	// The returned string lives no longer than the next iterator
+	// movement call.
+	//
+	inline int get_data(char*& data) const
+	{
+		data = (char*)dbt_.get_data();
+		return 0;
+	}
+
+	inline int get_data(string &data) const
+	{
+		data = (string::pointer) dbt_.get_data();
+		return 0;
+	}
+
+	inline int get_data(wchar_t*& data) const
+	{
+		data = (wchar_t*)dbt_.get_data();
+		return 0;
+	}
+
+#ifdef HAVE_WSTRING
+	inline int get_data(wstring &data) const
+	{
+		data = (wstring::pointer) dbt_.get_data();
+		return 0;
+	}
+#endif
+
+	////////////////////////////////////////////////////////////////////
+
+	// Supporting storing arbitrary type of sequence.
+	template <Typename T>
+	inline int get_data(T*& data) const
+	{
+		data = (T*)dbt_.get_data();
+		return 0;
+	}
+
+	inline int get_data(DataItem& data) const
+	{
+		int ret;
+
+		if (dbt_.get_data()) {
+			data.set_dbt(dbt_, false);
+			ret = 0;
+		} else
+			ret = -1;
+		return ret;
+	}
+
+	////////////////////////////////////////////////////////////////////
+	//
+	// Begin functions supporting Dbt storage.
+	//
+	// This member function allows storing a Dbt type, so that user can
+	// store the varying length data into Dbt.
+	//
+	// This method is required to copy a data element's bytes to another 
+	// Dbt object, used inside by dbstl.
+	// If there is no data return -1, if it has data return 0.
+	//
+	inline int get_data(Dbt& data) const
+	{
+		int ret;
+		void *addr;
+		u_int32_t sz;
+		DBT *pdbt = (DBT *)&dbt_, *pdata = (DBT *)&data;
+
+		if (pdbt->data) {
+			addr = pdata->data;
+			sz = pdbt->size;
+			if (pdata->ulen < sz) {
+				pdata->data = DbstlReAlloc(addr, sz);
+				pdata->size = sz;
+				pdata->ulen = sz;
+				pdata->flags |= DB_DBT_USERMEM;
+			} else
+				pdata->size = sz;
+			memcpy(pdata->data, pdbt->data, sz);
+			ret = 0;
+		} else
+			ret = -1;
+		return ret;
+	}
+
+	inline int get_data(DBT& data) const
+	{
+		int ret;
+		void*addr;
+		u_int32_t sz;
+
+		if (dbt_.get_data()) {
+			addr = data.data;
+			if (data.ulen < (sz = dbt_.get_size())) {
+				data.data = DbstlReAlloc(addr, sz);
+				// User need to free this memory
+				data.flags = data.flags | DB_DBT_USERMEM;
+				data.size = sz;
+				data.ulen = sz;
+			} else
+				data.size = sz;
+			memcpy(data.data, dbt_.get_data(), sz);
+			ret = 0;
+		} else
+			ret = -1;
+		return ret;
+	}
+
+	inline int get_data(DbstlDbt& data) const
+	{
+		int ret;
+		void *addr;
+		u_int32_t sz;
+		DBT *pdbt = (DBT *)&dbt_, *pdata = (DBT *)&data;
+
+		if (pdbt->data) {
+			addr = pdata->data;
+			sz = pdbt->size;
+			if (pdata->ulen < sz) {
+				pdata->data = DbstlReAlloc(addr, sz);
+				pdata->size = sz;
+				pdata->ulen = sz;
+				pdata->flags |= DB_DBT_USERMEM;
+			} else
+				pdata->size = sz;
+			memcpy(pdata->data, pdbt->data, sz);
+			ret = 0;
+		} else
+			ret = -1;
+		return ret;
+	}
+
+	////////////////////////////////////////////////////////////////////
+
+	// Deep copy in assignment and copy constructor.
+	inline const DbstlDbt& operator=(const DbstlDbt& t2)
+	{
+		set_dbt(t2, false);
+		return t2;
+	}
+
+	// Deep copy in assignment and copy constructor.
+	inline const Dbt& operator=(const Dbt& t2)
+	{
+		set_dbt(t2, false);
+		return t2;
+	}
+
+	// Deep copy in assignment and copy constructor.
+	inline const DBT& operator=(const DBT& t2)
+	{
+		set_dbt(t2, false);
+		return t2;
+	}
+
+	// Deep copy in assignment and copy constructor.
+	template <Typename T>
+	inline const T& operator = (const T&dt)
+	{
+
+		make_dbt(dt, false);
+		return dt;
+	}
+
+	// Generic way of storing an object or variable. Note that DataItem
+	// is not a class template but a class with function templates.
+	// Variable t locates on a consecutive chunk of memory, and objects 
+	// of T have the same size. 
+	//
+	template <Typename T>
+	void make_dbt(const T& dt, bool onstack)
+	{
+		typedef DbstlElemTraits<T> EM;
+		u_int32_t sz;
+		typename EM::ElemSizeFunct sizef;
+		typename EM::ElemCopyFunct copyf;
+		DBT *pdbt = (DBT *)&dbt_;
+
+		if ((sizef = EM::instance()->get_size_function()) != NULL)
+			sz = sizef(dt);
+		else
+			sz = sizeof(dt);
+
+		if (onstack) {
+			freemem();
+			pdbt->data = ((void*)&dt);
+			// We have to set DB_DBT_USERMEM for DB_THREAD to work.
+			pdbt->flags = (DB_DBT_USERMEM);
+			pdbt->size = (sz);
+			pdbt->ulen = (sz);
+			// This is a flag that this memory can't be freed
+			// because it is on stack.
+			pdbt->dlen = (INVALID_DLEN);
+			return;
+		}
+
+		// Not on stack, allocate enough space and "copy" the object
+		// using shall copy or customized copy.
+		if (pdbt->ulen < sz) {
+			pdbt->data = (DbstlReAlloc(pdbt->data, sz));
+			assert(pdbt->data != NULL);
+			pdbt->size = (sz);
+			pdbt->ulen = (sz);
+			pdbt->flags = (DB_DBT_USERMEM);
+		} else
+			pdbt->size = (sz);
+
+		if ((copyf = EM::instance()->get_copy_function()) != NULL)
+			copyf(pdbt->data, dt);
+		else
+			memcpy(pdbt->data, &dt, sz);
+	}
+
+	inline const char*&operator = (const char*&dt)
+	{
+		make_dbt(dt, false);
+		return dt;
+	}
+
+	inline const wchar_t*&operator = (const wchar_t*&dt)
+	{
+		make_dbt(dt, false);
+		return dt;
+	}
+
+	inline const string &operator=(const string &dt)
+	{
+		make_dbt(dt, false);
+		return dt;
+	}
+
+#ifdef HAVE_WSTRING
+	inline const wstring &operator=(const wstring &dt)
+	{
+		make_dbt(dt, false);
+		return dt;
+	}
+#endif
+
+	template <Typename T>
+	inline const T*&operator = (const T*&dt)
+	{
+		make_dbt(dt, false);
+		return dt;
+	}
+
+	inline const self& operator=(const self&dbt1)
+	{
+		ASSIGNMENT_PREDCOND(dbt1)
+		this->set_dbt(dbt1.dbt_, false);
+		return dbt1;
+	}
+
+	// Deep copy.
+	inline DataItem(const self&dbt1)
+	{
+		set_dbt(dbt1.dbt_, false);
+	}
+
+
+	inline DataItem(u_int32_t sz)
+	{
+		void *buf;
+		DBT *pdbt = (DBT *)&dbt_;
+
+		buf = NULL;
+		buf = DbstlMalloc(sz);
+		memset(buf, 0, sz);
+		pdbt->size = sz;
+		pdbt->ulen = sz;
+		pdbt->data = buf;
+		pdbt->flags = DB_DBT_USERMEM;
+	}
+
+	// Deep copy. The onstack parameter means whether the object referenced
+	// by this DataItem is on used with a function call where this DataItem
+	// object is used. If so, we don't deep copy the object, simply refer
+	// to its memory location. The meaining is the same for this parameter
+	// in constructors that follow.
+	inline DataItem(const Dbt&dbt2, bool onstack)
+	{
+		set_dbt(dbt2, onstack);
+	}
+	
+	inline DataItem(const DbstlDbt&dbt2, bool onstack)
+	{
+		set_dbt(dbt2, onstack);
+	}
+	
+	inline DataItem(const DBT&dbt2, bool onstack)
+	{
+		set_dbt(dbt2, onstack);
+	}
+
+	// Deep copy. There is a partial specialization for char*/wchar_t*/
+	// string/wstring.
+	template<Typename T>
+	inline DataItem(const T& dt, bool onstack)
+	{
+		make_dbt(dt, onstack);
+	}
+
+	inline ~DataItem(void)
+	{
+		freemem();
+	}
+
+protected:
+
+	// Store a char*/wchar_t* string. Need four versions for char*
+	// and wchar_t* respectively to catch all
+	// possibilities otherwise the most generic one will be called.
+	// Note that the two const decorator matters when doing type
+	// matching.
+	inline void make_dbt_chars(const char *t, bool onstack)
+	{
+		DBT *d = (DBT *)&dbt_;
+		u_int32_t sz;
+		sz = ((t == NULL) ? 
+		    sizeof(char) : 
+		    (u_int32_t)((strlen(t) + 1) * sizeof(char)));
+		if (!onstack) {
+			if (d->ulen < sz) {
+				d->flags |= DB_DBT_USERMEM;
+				d->data = DbstlReAlloc(d->data, sz);
+				d->ulen = sz;
+			}
+			d->size = sz;
+			if (t != NULL)
+				strcpy((char*)d->data, t);
+			else
+				memset(d->data, '\0', sizeof(char));
+		} else {
+			freemem();
+			d->data = ((t == NULL) ? (void *)"" : (void *)t);
+			d->size = sz;
+			d->ulen = sz;
+			d->flags = (DB_DBT_USERMEM);
+			d->dlen = (INVALID_DLEN);
+		}
+	}
+
+	inline void make_dbt_wchars(const wchar_t *t, bool onstack)
+	{
+		DBT *d = (DBT *)&dbt_;
+		u_int32_t sz;
+		sz = ((t == NULL) ? 
+		    sizeof(wchar_t) : 
+		    (u_int32_t)((wcslen(t) + 1) * sizeof(wchar_t)));
+		if (!onstack) {					
+			if (d->ulen < sz) {
+				d->flags |= DB_DBT_USERMEM;
+				d->data = DbstlReAlloc(d->data, sz);
+				d->ulen = sz;
+			}
+			d->size = sz;
+			if (t != NULL)
+				wcscpy((wchar_t*)d->data, t);
+			else
+				memset(d->data, L'\0', sizeof(wchar_t));
+		} else {
+			freemem();
+			d->data = ((t == NULL) ? (void *)L"" : (void *)t);
+			d->size = sz;
+			d->ulen = sz;
+			d->flags = (DB_DBT_USERMEM);
+			d->dlen = (INVALID_DLEN);
+		}
+	}
+
+	inline void make_dbt(const char*& t, bool onstack)
+	{
+		make_dbt_chars(t, onstack);
+	}
+
+	inline void make_dbt(const char* const& t, bool onstack)
+	{
+		make_dbt_chars(t, onstack);
+	}
+
+	inline void make_dbt(char*& t, bool onstack)
+	{
+		make_dbt_chars(t, onstack);
+	}
+
+	inline void make_dbt(char* const& t, bool onstack)
+	{
+		make_dbt_chars(t, onstack);
+	}
+
+	inline void make_dbt(const string& t, bool onstack)
+	{
+		make_dbt_chars(t.c_str(), onstack);
+	}
+
+	inline void make_dbt(const wchar_t*& t, bool onstack)
+	{
+		make_dbt_wchars(t, onstack);
+	}
+
+	inline void make_dbt(const wchar_t* const& t, bool onstack)
+	{
+		make_dbt_wchars(t, onstack);
+	}
+
+	inline void make_dbt(wchar_t*& t, bool onstack)
+	{
+		make_dbt_wchars(t, onstack);
+	}
+
+	inline void make_dbt(wchar_t* const& t, bool onstack)
+	{
+		make_dbt_wchars(t, onstack);
+	}
+
+#ifdef HAVE_WSTRING
+	inline void make_dbt(const wstring& t, bool onstack)
+	{
+		make_dbt_wchars(t.c_str(), onstack);
+	}
+#endif
+
+	template <Typename T>
+	void make_dbt_internal(const T*t, bool onstack)
+	{
+		u_int32_t i, sz, totalsz, sql;
+		DBT *pdbt = (DBT *)&dbt_;
+		typename DbstlElemTraits<T>::ElemSizeFunct szf = NULL;
+		typename DbstlElemTraits<T>::SequenceLenFunct
+		    seqlenf = NULL;
+
+		szf = DbstlElemTraits<T>::instance()->
+		    get_size_function();
+		seqlenf = DbstlElemTraits<T>::instance()->
+		    get_sequence_len_function();
+
+		assert(seqlenf != NULL);
+		sql = sz = (u_int32_t)seqlenf(t);
+		if (szf)
+			for (i = 0, totalsz = 0; i < sz; i++)
+				totalsz += szf(t[i]);
+		else
+			totalsz = sz * sizeof(T);
+
+		sz = totalsz;
+
+		if (onstack) {
+			freemem();
+			pdbt->data = (void *)t;
+			pdbt->size = sz;
+			pdbt->ulen = sz;
+			pdbt->flags = DB_DBT_USERMEM;
+			pdbt->dlen = INVALID_DLEN; // onstack flag;
+		} else {
+			// ulen stores the real length of the pointed memory.
+			if (pdbt->ulen < sz) {
+				pdbt->data = DbstlReAlloc(pdbt->data, sz);
+				pdbt->ulen = sz;
+				pdbt->flags |= DB_DBT_USERMEM;
+			}
+			pdbt->size = sz;
+
+			DbstlElemTraits<T>::instance()->
+			    get_sequence_copy_function()
+			        ((T *)pdbt->data, t, sql);
+		}
+	}
+
+	// Store a sequence of base type T. Need four versions to catch all
+	// possibilities otherwise the most generic one will be called.
+	template <Typename T>
+	inline void make_dbt(const T*const&tt, bool onstack)
+	{
+		make_dbt_internal((const T*)tt, onstack);
+	}
+	template <Typename T>
+	inline void make_dbt(T*const&tt, bool onstack)
+	{
+		make_dbt_internal((const T*)tt, onstack);
+	}
+	template <Typename T>
+	inline void make_dbt(T*&tt, bool onstack)
+	{
+		make_dbt_internal((const T*)tt, onstack);
+	}
+	template <Typename T>
+	inline void make_dbt(const T*&tt, bool onstack)
+	{
+		make_dbt_internal((const T*)tt, onstack);
+	}
+
+
+public:
+	inline DataItem(const char*& t, bool onstack)
+	{
+		make_dbt_chars(t, onstack);
+	}
+
+	inline DataItem(const char* const& t, bool onstack)
+	{
+		make_dbt_chars(t, onstack);
+	}
+
+	inline DataItem(char*& t, bool onstack)
+	{
+		make_dbt_chars(t, onstack);
+	}
+
+	inline DataItem(char* const& t, bool onstack)
+	{
+		make_dbt_chars(t, onstack);
+	}
+
+	inline DataItem(const string& t, bool onstack)
+	{
+		make_dbt_chars(t.c_str(), onstack);
+	}
+
+	inline DataItem(const wchar_t*& t, bool onstack)
+	{
+		make_dbt_wchars(t, onstack);
+	}
+
+	inline DataItem(const wchar_t* const& t, bool onstack)
+	{
+		make_dbt_wchars(t, onstack);
+	}
+
+	inline DataItem(wchar_t*& t, bool onstack)
+	{
+		make_dbt_wchars(t, onstack);
+	}
+
+	inline DataItem(wchar_t* const& t, bool onstack)
+	{
+		make_dbt_wchars(t, onstack);
+	}
+
+#ifdef HAVE_WSTRING
+	inline DataItem(const wstring& t, bool onstack)
+	{
+		make_dbt_wchars(t.c_str(), onstack);
+	}
+#endif
+	template<Typename T>
+	inline DataItem(T*&tt, bool onstack)
+	{
+		make_dbt_internal((const T*)tt, onstack);
+	}
+
+	template<Typename T>
+	inline DataItem(const T*&tt, bool onstack)
+	{
+		make_dbt_internal((const T*)tt, onstack);
+	}
+
+	template<Typename T>
+	inline DataItem(T*const&tt, bool onstack)
+	{
+		make_dbt_internal((const T*)tt, onstack);
+	}
+
+	template<Typename T>
+	inline DataItem(const T*const&tt, bool onstack)
+	{
+		make_dbt_internal((const T*)tt, onstack);
+	}
+
+
+}; // DataItem<>
+
+bool operator==(const Dbt&d1, const Dbt&d2);
+bool operator==(const DBT&d1, const DBT&d2);
+END_NS
+
+#endif // !_DB_STL_DBT_H
diff --git a/stl/dbstl_element_ref.h b/stl/dbstl_element_ref.h
new file mode 100644
index 0000000..492fdc7
--- /dev/null
+++ b/stl/dbstl_element_ref.h
@@ -0,0 +1,873 @@
+/*-
+ * See the file LICENSE for redistribution information.
+ *
+ * Copyright (c) 2009 Oracle.  All rights reserved.
+ *
+ * $Id$
+ */
+
+#ifndef _DB_STL_KDPAIR_H
+#define _DB_STL_KDPAIR_H
+
+#include <iostream>
+
+#include "dbstl_common.h"
+#include "dbstl_dbt.h"
+#include "dbstl_exception.h"
+#include "dbstl_base_iterator.h"
+#include "dbstl_utility.h"
+
+START_NS(dbstl)
+
+using std::istream;
+using std::ostream;
+using std::basic_ostream;
+using std::basic_istream;
+
+template <Typename ddt>
+class db_base_iterator;
+template <Typename ddt>
+class ElementHolder;
+
+/** \ingroup dbstl_helper_classes
+\defgroup Element_wrappers ElementRef and ElementHolder wrappers.
+An ElementRef and ElementHolder object represents the reference to the 
+data element referenced by an iterator. Each iterator 
+object has an ElementRef or ElementHolder object that
+stores the data element that the iterator points to.
+
+The ElementHolder class is used to store primitive types into STL containers.
+
+The ElementRef class is used to store other types into STL containers.
+
+The ElementRef and ElementHolder classes have identical interfaces, and are
+treated the same by other STL classes. Since the ElementRef class inherits
+from the template data class, all methods have a _DB_STL_ prefix to avoid name
+clashes.
+
+An ElementRef or ElementHolder class corresponds to a single iterator instance.
+An Element object is generally owned by an iterator object. The ownership
+relationship is swapped in some specific situations, specifically for the 
+dereference and array index operator.
+@{
+*/
+/// ElementRef element wrapper for classes and structures.
+/// \sa ElementHolder
+template <Typename ddt>
+class _exported ElementRef : public ddt
+{
+public:
+	typedef ElementRef<ddt> self;
+	typedef ddt base;
+	typedef db_base_iterator<ddt> iterator_type;
+	typedef ddt content_type; // Used by assoc classes.
+
+private:
+	// The iterator pointing the data element stored in this object.
+	iterator_type *_DB_STL_itr_;
+
+	// Whether or not to delete itr on destruction, by default it is
+	// false because this object is supposed to live in the lifetime of
+	// its _DB_STL_itr_ owner. But there is one exception: in
+	// db_vector<>::operator[]/front/back and db_map<>::operator[]
+	// functions, an ElementRef<T> object has to be
+	// returned instead of its reference, thus the
+	// returned ElementRef<> has to live longer than its _DB_STL_itr_,
+	// thus we new an iterator, and call _DB_STL_SetDelItr() method, 
+	// setting this member to true,
+	// to tell this object that it should delete the
+	// _DB_STL_itr_ iterator on destruction, and duplicate the _DB_STL_itr_
+	// iterator on copy construction. Although
+	// std::vector<> returns reference rather than value, this is not a
+	// problem because the returned ElementRef<> will duplicate cursor and
+	// still points to the same key/data pair.
+	//
+	mutable bool _DB_STL_delete_itr_;
+
+public:
+	////////////////////////////////////////////////////////////////////
+	//
+	// Begin constructors and destructor.
+	//
+	/// \name Constructors and destructor.
+	//@{
+	/// Destructor.
+	~ElementRef() {
+		if (_DB_STL_delete_itr_) {
+			// Prevent recursive destruction.
+			_DB_STL_delete_itr_ = false;
+			_DB_STL_itr_->delete_me();
+		}
+	}
+
+	/// Constructor.
+	/// If the pitr parameter is NULL or the default value is used, the
+	/// object created is a simple wrapper and not connected to a container.
+	/// If a valid iterator parameter is passed in, the wrapped element will
+	/// be associated with the matching key/data pair in the underlying
+	/// container.
+	/// \param pitr The iterator owning this object.
+	explicit ElementRef(iterator_type *pitr = NULL)
+	{
+		_DB_STL_delete_itr_ = false;
+		_DB_STL_itr_ = pitr;
+	}
+
+	/// Constructor.
+	/// Initializes an ElementRef wrapper without an iterator. It can only
+	/// be used to wrap a data element in memory, it can't access an
+	/// unerlying database. 
+	/// \param dt The base class object to initialize this object.
+	ElementRef(const ddt &dt) : ddt(dt)
+	{
+		_DB_STL_delete_itr_ = false;
+		_DB_STL_itr_ = NULL;
+	}
+
+	/// Copy constructor.
+	/// The constructor takes a "deep" copy. The created object will be 
+	/// identical to, but independent from the original object.
+	/// \param other The object to clone from.
+	ElementRef(const self &other) : ddt(other)
+	{
+		// Duplicate iterator if this object lives longer than
+		// _DB_STL_itr_.
+		_DB_STL_delete_itr_ = other._DB_STL_delete_itr_;
+		if (_DB_STL_delete_itr_) {
+			// Avoid recursive duplicate iterator calls.
+			other._DB_STL_delete_itr_ = false;
+			_DB_STL_itr_ = other._DB_STL_itr_->dup_itr();
+			other._DB_STL_delete_itr_ = true;
+		} else
+			_DB_STL_itr_ = other._DB_STL_itr_;
+	}
+	//@}
+	////////////////////////////////////////////////////////////////////
+
+	/// \name Assignment operators.
+	/// The assignment operators are used to store right-values into the
+	/// wrapped object, and also to store values into an underlying 
+	/// container.
+	//@{
+	/// Assignment Operator.
+	/// \param dt2 The data value to assign with.
+	/// \return The object dt2's reference.
+	inline const ddt& operator=(const ddt& dt2)
+	{
+		*((ddt*)this) = dt2;
+		if (_DB_STL_itr_ != NULL) {
+			if (!_DB_STL_itr_->is_set_iterator())
+				_DB_STL_itr_->replace_current(dt2);
+			else
+				_DB_STL_itr_->replace_current_key(dt2);
+		}
+		return dt2;
+	}
+
+	/// Assignment Operator.
+	/// \param me The object to assign with.
+	/// \return The object me's reference.
+	inline const self& operator=(const self& me)
+	{
+		ASSIGNMENT_PREDCOND(me)
+		*((ddt*)this) = (ddt)me;
+		if (_DB_STL_itr_ != NULL) {
+			// This object is the reference of an valid data
+			// element, so we must keep it that way, we don't
+			// use me's iterator here.
+			if (!_DB_STL_itr_->is_set_iterator())
+				_DB_STL_itr_->replace_current(
+				    me._DB_STL_value());
+			else
+				_DB_STL_itr_->replace_current_key(
+				    me._DB_STL_value());
+		} else if (me._DB_STL_delete_itr_) {
+			// Duplicate an iterator from me.
+			_DB_STL_delete_itr_ = true;
+			me._DB_STL_delete_itr_ = false;
+			_DB_STL_itr_ = me._DB_STL_itr_->dup_itr();
+			me._DB_STL_delete_itr_ = true;
+		}
+
+		return me;
+	}
+	//@}
+
+	/// Function to store the data element.
+	/// The user needs to call this method after modifying the underlying
+	/// object, so that the version stored in the container can be updated.
+	/// 
+	/// When db_base_iterator's directdb_get_ member is true, this function
+	/// must be called after modifying the data member and before any
+	/// subsequent container iterator dereference operations. If this step
+	/// is not carried out any changes will be lost.
+	///
+	/// If the data element is changed via ElementHolder<>::operator=(), 
+	/// you don't need to call this function.
+	inline void _DB_STL_StoreElement()
+	{
+		assert(_DB_STL_itr_ != NULL);
+		_DB_STL_itr_->replace_current(*this);
+	}
+
+	/// Returns the data element this wrapper object wraps.
+	inline const ddt& _DB_STL_value() const
+	{
+		return *((ddt*)this);
+	}
+
+	/// Returns the data element this wrapper object wraps.
+	inline ddt& _DB_STL_value()
+	{
+		return *((ddt*)this);
+	}
+
+#ifndef DOXYGEN_CANNOT_SEE_THIS
+	////////////////////////////////////////////////////////////////////
+	//
+	// The following methods are not part of the official public API,
+	// but can't be declared as protected, since it is not possible
+	// to declare template-specialised classes as friends.
+	//
+
+	// Call this function to tell this object that it should delete the
+	// _DB_STL_itr_ iterator because that iterator was allocated in
+	// the heap. Methods like db_vector/db_map<>::operator[] should call
+	// this function.
+	inline void _DB_STL_SetDelItr()
+	{
+		_DB_STL_delete_itr_ = true;
+	}
+
+	// Only copy data into this object, do not store into database.
+	inline void _DB_STL_CopyData(const self&dt2)
+	{
+		*((ddt*)this) = (ddt)dt2;
+	}
+
+	inline void _DB_STL_CopyData(const ddt&dt2)
+	{
+		*((ddt*)this) = dt2;
+	}
+
+	// Following functions are prefixed with _DB_STL_ to avoid
+	// potential name clash with ddt members.
+	//
+	inline iterator_type* _DB_STL_GetIterator() const
+	{
+	       return _DB_STL_itr_;
+	}
+
+	inline int _DB_STL_GetData(ddt& d) const
+	{
+		d = *((ddt*)this);
+		return 0;
+	}
+
+	inline void _DB_STL_SetIterator(iterator_type*pitr)
+	{
+		_DB_STL_itr_ = pitr;
+	}
+
+	inline void _DB_STL_SetData(const ddt&d)
+	{
+		*(ddt*)this = d;
+	}
+	////////////////////////////////////////////////////////////////////
+
+}; // ElementRef<>
+template<typename T>
+class DbstlSeqWriter;
+#else
+};
+#endif // DOXYGEN_CANNOT_SEE_THIS
+
+
+// The ElementHolder class must have an identical public interface to 
+// the ElementRef class.
+/// A wrapper class for primitive types. It has identical usage and public 
+/// interface to the ElementRef class.
+/// \sa ElementRef. 
+template <typename ptype>
+class _exported ElementHolder
+{
+protected:
+	typedef ElementHolder<ptype> self;
+
+
+	inline void _DB_STL_put_new_value_to_db()
+	{
+		if (_DB_STL_itr_ != NULL) {
+			if (!_DB_STL_itr_->is_set_iterator())
+				_DB_STL_itr_->replace_current(dbstl_my_value_);
+			else
+				_DB_STL_itr_->replace_current_key(
+				    dbstl_my_value_);
+		}
+	}
+
+	inline void _DB_STL_put_new_value_to_db(const self &me)
+	{
+		if (_DB_STL_itr_ != NULL) {
+			if (!_DB_STL_itr_->is_set_iterator())
+				_DB_STL_itr_->replace_current(dbstl_my_value_);
+			else
+				_DB_STL_itr_->replace_current_key(
+				    dbstl_my_value_);
+		} else if (me._DB_STL_delete_itr_) {
+			// Duplicate an iterator from me.
+			_DB_STL_delete_itr_ = true;
+			me._DB_STL_delete_itr_ = false;
+			_DB_STL_itr_ = me._DB_STL_itr_->dup_itr();
+			me._DB_STL_delete_itr_ = true;
+		}
+	}
+
+
+
+public:
+	typedef ptype type1;
+	typedef db_base_iterator<ptype> iterator_type;
+	typedef ptype content_type;
+
+	////////////////////////////////////////////////////////////////////
+	//
+	// Begin constructors and destructor.
+	//
+	/// \name Constructors and destructor.
+	//@{
+	/// Constructor.
+	/// If the pitr parameter is NULL or the default value is used, the
+	/// object created is a simple wrapper and not connected to a container.
+	/// If a valid iterator parameter is passed in, the wrapped element will
+	/// be associated with the matching key/data pair in the underlying
+	/// container.
+	/// \param pitr The iterator owning this object.
+	explicit inline ElementHolder(iterator_type* pitr = NULL)
+	{
+		_DB_STL_delete_itr_ = false;
+		_DB_STL_itr_ = pitr;
+		dbstl_str_buf_ = NULL;
+		dbstl_str_buf_len_ = 0;
+		memset(&dbstl_my_value_, 0, sizeof(dbstl_my_value_));
+	}
+
+	/// Constructor.
+	/// Initializes an ElementRef wrapper without an iterator. It can only
+	/// be used to wrap a data element in memory, it can't access an
+	/// unerlying database. 
+	/// \param dt The base class object to initialize this object.
+	inline ElementHolder(const ptype&dt)
+	{
+		dbstl_str_buf_ = NULL;
+		dbstl_str_buf_len_ = 0;
+		_DB_STL_delete_itr_ = false;
+		_DB_STL_itr_ = NULL;
+		_DB_STL_CopyData_int(dt);
+	}
+
+	/// Copy constructor.
+	/// The constructor takes a "deep" copy. The created object will be 
+	/// identical to, but independent from the original object.
+	/// \param other The object to clone from.
+	inline ElementHolder(const self& other)
+	{
+		dbstl_str_buf_ = NULL;
+		dbstl_str_buf_len_ = 0;
+		_DB_STL_delete_itr_ = other._DB_STL_delete_itr_;
+		_DB_STL_CopyData(other);
+
+		// Duplicate iterator if this object lives longer than
+		// _DB_STL_itr_.
+		_DB_STL_delete_itr_ = other._DB_STL_delete_itr_;
+		if (_DB_STL_delete_itr_) {
+			// Avoid recursive duplicate iterator calls.
+			other._DB_STL_delete_itr_ = false;
+			_DB_STL_itr_ = other._DB_STL_itr_->dup_itr();
+			other._DB_STL_delete_itr_ = true;
+		} else
+			_DB_STL_itr_ = other._DB_STL_itr_;
+	}
+
+	/// Destructor.
+	~ElementHolder() {
+		if (_DB_STL_delete_itr_) {
+			_DB_STL_delete_itr_ = false;
+			_DB_STL_itr_->delete_me();
+		}
+		if (dbstl_str_buf_) {
+			free(dbstl_str_buf_);
+			dbstl_str_buf_ = NULL;
+		}
+	}
+	//@}
+	////////////////////////////////////////////////////////////////////
+
+	/// This operator is a type converter. Where an automatic type 
+	/// conversion is needed, this function is called to convert this 
+	/// object into the primitive type it wraps.
+	operator ptype () const
+	{
+		return dbstl_my_value_;
+	}
+
+	// ElementHolder is a wrapper for primitive types, and backed by db,
+	// so we need to override all assignment operations to store updated
+	// value to database. We don't need to implement other operators for
+	// primitive types because we have a convert operator which can
+	// automatically convert to primitive type and use its C++ built in
+	// operator.
+	//
+	/** \name Math operators.
+	ElementHolder class templates also have all C/C++ self mutating 
+	operators for numeric primitive types, including:
+	+=, -=, *=, /=, %=, <<=, >>=, &=, |=, ^=, ++, --
+	These operators should not be used when ddt is a sequence pointer type
+	like char* or wchar_t* or T*, otherwise the behavior is undefined. 
+	These methods exist only to override default bahavior to store the 
+	new updated value, otherwise, the type convert operator could have 
+	done all the job.
+	As you know, some of them are not applicable to float or double types 
+	or ElementHolder wrapper types for float/double types. 
+	These operators not only modifies the cached data element, but also 
+	stores new value to database if it associates a database key/data pair.
+	@{
+	*/
+	template <Typename T2>
+	const self& operator +=(const ElementHolder<T2> &p2)
+	{
+		dbstl_my_value_ += p2.dbstl_my_value_;
+		_DB_STL_put_new_value_to_db(p2);
+		return *this;
+	}
+
+	template <Typename T2>
+	const self& operator -=(const ElementHolder<T2> &p2)
+	{
+		dbstl_my_value_ -= p2.dbstl_my_value_;
+		_DB_STL_put_new_value_to_db(p2);
+		return *this;
+	}
+	template <Typename T2>
+	const self& operator *=(const ElementHolder<T2> &p2)
+	{
+		dbstl_my_value_ *= p2.dbstl_my_value_;
+		_DB_STL_put_new_value_to_db(p2);
+		return *this;
+	}
+	template <Typename T2>
+	const self& operator /=(const ElementHolder<T2> &p2)
+	{
+		dbstl_my_value_ /= p2.dbstl_my_value_;
+		_DB_STL_put_new_value_to_db(p2);
+		return *this;
+	}
+	template <Typename T2>
+	const self& operator %=(const ElementHolder<T2> &p2)
+	{
+		dbstl_my_value_ %= p2.dbstl_my_value_;
+		_DB_STL_put_new_value_to_db(p2);
+		return *this;
+	}
+
+	template <Typename T2>
+	const self& operator &=(const ElementHolder<T2> &p2)
+	{
+		dbstl_my_value_ &= p2.dbstl_my_value_;
+		_DB_STL_put_new_value_to_db(p2);
+		return *this;
+	}
+	template <Typename T2>
+	const self& operator |=(const ElementHolder<T2> &p2)
+	{
+		dbstl_my_value_ |= p2.dbstl_my_value_;
+		_DB_STL_put_new_value_to_db(p2);
+		return *this;
+	}
+	template <Typename T2>
+	const self& operator ^=(const ElementHolder<T2> &p2)
+	{
+		dbstl_my_value_ ^= p2.dbstl_my_value_;
+		_DB_STL_put_new_value_to_db(p2);
+		return *this;
+	}
+
+	const self& operator >>=(size_t n)
+	{
+		dbstl_my_value_ >>= n;
+		_DB_STL_put_new_value_to_db();
+		return *this;
+	}
+
+	const self& operator <<=(size_t n)
+	{
+		dbstl_my_value_ <<= n;
+		_DB_STL_put_new_value_to_db();
+		return *this;
+	}
+
+	const self& operator ^=(const self &p2)
+	{
+		dbstl_my_value_ ^= p2.dbstl_my_value_;
+		_DB_STL_put_new_value_to_db();
+		return *this;
+	}
+
+	const self& operator &=(const self &p2)
+	{
+		dbstl_my_value_ &= p2.dbstl_my_value_;
+		_DB_STL_put_new_value_to_db();
+		return *this;
+	}
+
+	const self& operator |=(const self &p2)
+	{
+		dbstl_my_value_ |= p2.dbstl_my_value_;
+		_DB_STL_put_new_value_to_db();
+		return *this;
+	}
+
+	const self& operator %=(const self &p2)
+	{
+		dbstl_my_value_ %= p2.dbstl_my_value_;
+		_DB_STL_put_new_value_to_db();
+		return *this;
+	}
+
+	const self& operator +=(const self &p2)
+	{
+		dbstl_my_value_ += p2.dbstl_my_value_;
+		_DB_STL_put_new_value_to_db();
+		return *this;
+	}
+	const self& operator -=(const self &p2)
+	{
+		dbstl_my_value_ -= p2.dbstl_my_value_;
+		_DB_STL_put_new_value_to_db();
+		return *this;
+	}
+	const self& operator /=(const self &p2)
+	{
+		dbstl_my_value_ /= p2.dbstl_my_value_;
+		_DB_STL_put_new_value_to_db();
+		return *this;
+	}
+	const self& operator *=(const self &p2)
+	{
+		dbstl_my_value_ *= p2.dbstl_my_value_;
+		_DB_STL_put_new_value_to_db();
+		return *this;
+	}
+
+	self& operator++()
+	{
+		dbstl_my_value_++;
+		_DB_STL_put_new_value_to_db();
+		return *this;
+	}
+
+	self operator++(int)
+	{
+		self obj(*this);
+		dbstl_my_value_++;
+		_DB_STL_put_new_value_to_db();
+		return obj;
+	}
+
+	self& operator--()
+	{
+		dbstl_my_value_--;
+		_DB_STL_put_new_value_to_db();
+		return *this;
+	}
+
+	self operator--(int)
+	{
+		self obj(*this);
+		dbstl_my_value_--;
+		_DB_STL_put_new_value_to_db();
+		return obj;
+	}
+
+	inline const ptype& operator=(const ptype& dt2)
+	{
+		_DB_STL_CopyData_int(dt2);
+		_DB_STL_put_new_value_to_db();
+		return dt2;
+	}
+
+	inline const self& operator=(const self& dt2)
+	{
+		ASSIGNMENT_PREDCOND(dt2)
+		_DB_STL_CopyData(dt2);
+		_DB_STL_put_new_value_to_db(dt2);
+		return dt2;
+	}
+	//@}
+	
+	/// Returns the data element this wrapper object wraps;
+	inline const ptype& _DB_STL_value() const
+	{
+		return dbstl_my_value_;
+	}
+
+	/// Returns the data element this wrapper object wraps;
+	inline ptype&_DB_STL_value()
+	{
+		return dbstl_my_value_;
+	}
+	
+	/// Function to store the data element.
+	/// The user needs to call this method after modifying the underlying
+	/// object, so that the version stored in the container can be updated.
+	/// 
+	/// When db_base_iterator's directdb_get_ member is true, this function
+	/// must be called after modifying the data member and before any
+	/// subsequent container iterator dereference operations. If this step
+	/// is not carried out any changes will be lost.
+	///
+	/// If the data element is changed via ElementHolder<>::operator=(), 
+	/// you don't need to call this function.
+	inline void _DB_STL_StoreElement()
+	{
+		assert(_DB_STL_itr_ != NULL);
+		_DB_STL_itr_->replace_current(dbstl_my_value_);
+	}
+
+#ifndef DOXYGEN_CANNOT_SEE_THIS
+	////////////////////////////////////////////////////////////////////
+	//
+	// The following methods are not part of the official public API,
+	// but can't be declared as protected, since it is not possible
+	// to declare template-specialised classes as friends.
+	//
+	inline void _DB_STL_CopyData(const self&dt2)
+	{
+		_DB_STL_CopyData_int(dt2.dbstl_my_value_);
+	}
+
+	template<Typename T>
+	inline void _DB_STL_CopyData_int(const T&src)
+	{
+		dbstl_my_value_ = src;
+	}
+
+	// Try to catch all types of pointers.
+	template<Typename T>
+	inline void _DB_STL_CopyData_int(T* const &src)
+	{
+		DbstlSeqWriter<T>::copy_to_holder((ElementHolder<T *> *)this, 
+		    (T *)src);	
+	}
+
+	template<Typename T>
+	inline void _DB_STL_CopyData_int(const T* const &src)
+	{
+		DbstlSeqWriter<T>::copy_to_holder((ElementHolder<T *> *)this, 
+		    (T *)src);	
+	}
+
+	template<Typename T>
+	inline void _DB_STL_CopyData_int(T* &src)
+	{
+		DbstlSeqWriter<T>::copy_to_holder((ElementHolder<T *> *)this, 
+		    (T *)src);	
+	}
+
+	template<Typename T>
+	inline void _DB_STL_CopyData_int(const T*&src)
+	{
+		DbstlSeqWriter<T>::copy_to_holder((ElementHolder<T *> *)this, 
+		    (T *)src);	
+	}
+
+	inline iterator_type* _DB_STL_GetIterator() const
+	{
+	       return _DB_STL_itr_;
+	}
+
+	inline int _DB_STL_GetData(ptype& d) const
+	{
+		d = dbstl_my_value_;
+		return 0;
+	}
+
+	inline void _DB_STL_SetIterator(iterator_type*pitr)
+	{
+		_DB_STL_itr_ = pitr;
+	}
+
+	inline void _DB_STL_SetData(const ptype&d)
+	{
+		_DB_STL_CopyData_int(d);
+	}
+
+	inline void _DB_STL_SetDelItr()
+	{
+		_DB_STL_delete_itr_ = true;
+	}
+
+	// The two member has to be public for DbstlSeqWriter to access, 
+	// but can't be accessed by user. 
+	size_t dbstl_str_buf_len_;
+	void *dbstl_str_buf_; // Stores a sequence, used when ptype is T*
+
+	iterator_type *_DB_STL_itr_;
+	ptype dbstl_my_value_;
+	mutable bool _DB_STL_delete_itr_;
+};
+#else
+};
+#endif // DOXYGEN_CANNOT_SEE_THIS
+//@} // Element_wrappers
+//@} //dbstl_helper_classes
+
+// These operators help reading from and writing to iostreams, if the wrapped
+// data type has iostream operators.
+template<Typename _CharT, Typename _Traits, Typename ddt>
+basic_istream<_CharT,_Traits>&
+operator>>( basic_istream<_CharT,_Traits> & in, ElementRef<ddt>&p)
+{
+	in>>(ddt)p;
+	return in;
+}
+
+template<Typename _CharT, Typename _Traits, Typename ddt>
+basic_ostream<_CharT,_Traits>&
+operator<<( basic_ostream<_CharT,_Traits> & out,
+    const ElementRef<ddt>&p)
+{
+	out<<(ddt)p;
+	return out;
+}
+
+template<Typename _CharT, Typename _Traits, Typename ddt>
+basic_istream<_CharT,_Traits>&
+operator>>( basic_istream<_CharT,_Traits> & in, ElementHolder<ddt>&p)
+{
+	in>>p._DB_STL_value();
+	return in;
+}
+
+template<Typename _CharT, Typename _Traits, Typename ddt>
+basic_ostream<_CharT,_Traits>&
+operator<<( basic_ostream<_CharT,_Traits> & out,
+    const ElementHolder<ddt>&p)
+{
+	out<<p._DB_STL_value();
+	return out;
+}
+
+template<typename T>
+class _exported DbstlSeqWriter
+{
+public:
+	typedef ElementHolder<T *> HolderType;
+	static void copy_to_holder(HolderType *holder, T *src)
+	{
+		size_t i, slen, sql;
+
+		if (src == NULL) {
+			free(holder->dbstl_str_buf_);
+			holder->dbstl_str_buf_ = NULL;
+			holder->dbstl_my_value_ = NULL;
+			return;
+		}
+		if (holder->dbstl_str_buf_len_ > DBSTL_MAX_DATA_BUF_LEN) {
+			free(holder->dbstl_str_buf_);
+			holder->dbstl_str_buf_ = NULL;
+		}
+
+		typedef DbstlElemTraits<T> DM;
+		typename DM::SequenceCopyFunct seqcpy =
+		    DM::instance()->get_sequence_copy_function();
+		typename DM::SequenceLenFunct seqlen =
+		    DM::instance()->get_sequence_len_function();
+		typename DM::ElemSizeFunct elemszf = 
+		    DM::instance()->get_size_function();
+
+		assert(seqcpy != NULL && seqlen != NULL);
+		sql = seqlen(src);
+		if (elemszf == NULL)
+			slen = sizeof(T) * (sql + 1);
+		else
+			// We don't add the terminating object if it has one.
+			// So the registered functions should take care of it.
+			for (slen = 0, i = 0; i < sql; i++)
+				slen += elemszf(src[i]);
+
+		if (slen > holder->dbstl_str_buf_len_)
+			holder->dbstl_str_buf_ = DbstlReAlloc(
+			    holder->dbstl_str_buf_, 
+			    holder->dbstl_str_buf_len_ = slen);
+
+		seqcpy((T*)holder->dbstl_str_buf_, src, sql);
+		holder->dbstl_my_value_ = (T*)holder->dbstl_str_buf_;
+	}
+};
+
+template<>
+class _exported DbstlSeqWriter<char>
+{
+public:
+	typedef ElementHolder<char *> HolderType;
+	static void copy_to_holder(HolderType *holder, char *src)
+	{
+		size_t slen;
+
+		if (src == NULL) {
+			free(holder->dbstl_str_buf_);
+			holder->dbstl_str_buf_ = NULL;
+			holder->dbstl_my_value_ = NULL;
+			return;
+		}
+		if (holder->dbstl_str_buf_len_ > DBSTL_MAX_DATA_BUF_LEN) {
+			free(holder->dbstl_str_buf_);
+			holder->dbstl_str_buf_ = NULL;
+		}
+
+		slen = sizeof(char) * (strlen(src) + 1);
+		if (slen > holder->dbstl_str_buf_len_)
+			holder->dbstl_str_buf_ = DbstlReAlloc(
+			    holder->dbstl_str_buf_, 
+			    (u_int32_t)(holder->dbstl_str_buf_len_ = slen));
+
+		strcpy((char*)holder->dbstl_str_buf_, src);
+		holder->dbstl_my_value_ = (char*)holder->dbstl_str_buf_;
+
+	}
+};
+
+template<>
+class _exported DbstlSeqWriter<wchar_t>
+{
+public:
+	typedef ElementHolder<wchar_t *> HolderType;
+	static void copy_to_holder(HolderType *holder, wchar_t *src)
+	{
+		size_t slen;
+
+		if (src == NULL) {
+			free(holder->dbstl_str_buf_);
+			holder->dbstl_str_buf_ = NULL;
+			holder->dbstl_my_value_ = NULL;
+			return;
+		}
+		if (holder->dbstl_str_buf_len_ > DBSTL_MAX_DATA_BUF_LEN) {
+			free(holder->dbstl_str_buf_);
+			holder->dbstl_str_buf_ = NULL;
+		}
+
+		slen = sizeof(wchar_t) * (wcslen(src) + 1);
+		if (slen > holder->dbstl_str_buf_len_)
+			holder->dbstl_str_buf_ = DbstlReAlloc(
+			    holder->dbstl_str_buf_, 
+			    holder->dbstl_str_buf_len_ = slen);
+
+		wcscpy((wchar_t*)holder->dbstl_str_buf_, src);
+		holder->dbstl_my_value_ = (wchar_t*)holder->dbstl_str_buf_;
+	}
+};
+END_NS
+
+#endif// !_DB_STL_KDPAIR_H
diff --git a/stl/dbstl_exception.h b/stl/dbstl_exception.h
new file mode 100644
index 0000000..a0ff476
--- /dev/null
+++ b/stl/dbstl_exception.h
@@ -0,0 +1,257 @@
+/*-
+ * See the file LICENSE for redistribution information.
+ *
+ * Copyright (c) 2009 Oracle.  All rights reserved.
+ *
+ * $Id$
+ */
+
+#ifndef _DB_STL_EXCEPTION_H
+#define _DB_STL_EXCEPTION_H
+
+#include <cstring>
+#include <cstdlib>
+#include <cstdio>
+
+#include <iostream>
+#include <exception>
+
+#include "dbstl_common.h"
+
+START_NS(dbstl)
+
+using std::cerr;
+
+// Internally used only.
+void _exported throw_bdb_exception(const char *caller, int err_ret);
+#define COPY_CONSTRUCTOR(type) type(const type& t) : DbstlException(t){}
+
+/** \defgroup Exception_classes_group dbstl exception classes
+dbstl throws several types of exceptions on several kinds of errors, the
+exception classes form a class hiarachy. First, there is the DbstlException,
+which is the base class for all types of dbstl specific concrete exception 
+classes.
+DbstlException inherits from the class DbException of Berkeley DB C++ API. Since
+DbException class inherits from C++ STL exception base class std::exception, 
+you can make use of all Berkeley DB C++ and dbstl API exceptions in the same
+way you use the C++ std::exception class. 
+
+Besides exceptions of DbstlException and its subclasses, dbstl may also
+throw exceptions of DbException and its subclasses, which happens when a 
+Berkeley DB call failed. So you should use the same way you catch Berkeley DB
+C++ API exceptions when you want to catch exceptions throw by Berkeley DB 
+operations.
+
+When an exception occurs, dbstl initialize an local exception object on the 
+stack and throws the exception object, so you should catch an exception like 
+this:
+
+try {
+	// dbstl operations
+}
+catch(DbstlException ex){
+	// Exception handling
+	throw ex; // Optionally throw ex again
+}
+
+@{
+*/
+
+/// Base class of all dbstl exception classes. It is derived from Berkeley 
+/// DB C++ API DbException class to maintain consistency with all 
+/// Berkeley DB exceptions.
+///
+class _exported DbstlException : public DbException
+{
+public:
+	explicit DbstlException(const char *msg) : DbException(msg) {}
+	DbstlException(const char *msg, int err) : DbException(msg, err) {}
+	DbstlException(const DbstlException&ex) : DbException(ex) {}
+	explicit DbstlException(int err) : DbException(err) {}
+	DbstlException(const char *prefix, const char *msg, int err) : 
+	    DbException(prefix, msg, err) {}
+
+	const DbstlException& operator=(const DbstlException&exobj)
+	{
+		ASSIGNMENT_PREDCOND(exobj)
+		DbException::operator =
+		    (dynamic_cast<const DbException&>(exobj));
+		return exobj;
+	}
+
+	virtual ~DbstlException() throw(){}
+};
+
+/// Failed to allocate memory because memory is not enough.
+class _exported NotEnoughMemoryException : public DbstlException
+{
+	size_t failed_size; // The size of the failed allocation.
+public:
+	NotEnoughMemoryException(const char *msg, size_t sz) 
+	    : DbstlException(msg)
+	{
+		failed_size = sz;
+	}
+
+	 
+	NotEnoughMemoryException(const NotEnoughMemoryException &ex)
+	    : DbstlException(ex)
+	{
+		this->failed_size = ex.failed_size;
+	}
+};
+
+/// The iterator has inconsistent status, it is unable to be used any more.
+class _exported InvalidIteratorException : public DbstlException
+{
+public:
+	InvalidIteratorException() : DbstlException("Invalid Iterator")
+	{
+	}
+
+	explicit InvalidIteratorException(int error_code) : 
+	    DbstlException("Invalid Iterator", error_code)
+	{
+	}
+	COPY_CONSTRUCTOR(InvalidIteratorException)
+};
+
+/// The cursor has inconsistent status, it is unable to be used any more.
+class _exported InvalidCursorException : public DbstlException
+{
+public:
+	InvalidCursorException() : DbstlException("Invalid cursor")
+	{
+	}
+
+	explicit InvalidCursorException(int error_code) : 
+	    DbstlException("Invalid cursor", error_code)
+	{
+	}
+	COPY_CONSTRUCTOR(InvalidCursorException)
+};
+
+/// The Dbt object has inconsistent status or has no valid data, it is unable
+/// to be used any more.
+class _exported InvalidDbtException : public DbstlException
+{
+public:
+	InvalidDbtException() : DbstlException("Invalid Dbt object")
+	{
+	}
+
+	explicit InvalidDbtException(int error_code) : 
+	    DbstlException("Invalid Dbt object", error_code)
+	{
+	}
+	COPY_CONSTRUCTOR(InvalidDbtException)
+};
+
+/// The assertions inside dbstl failed. The code file name and line number
+/// will be passed to the exception object of this class.
+class _exported FailedAssertionException : public DbstlException
+{
+private:
+	char *err_msg_;
+public:
+	virtual const char *what() const throw()
+	{
+		return err_msg_;
+	}
+
+	FailedAssertionException(const char *fname, size_t lineno, 
+	    const char *msg) : DbstlException(0)
+	{
+		u_int32_t sz;
+		char *str;
+		
+		str = (char *)DbstlMalloc(sz = (u_int32_t)(strlen(msg) + 
+		    strlen(fname) + 128));
+		_snprintf(str, sz, 
+		    "In file %s at line %u, %s expression failed", 
+		    fname, (unsigned int)lineno, msg);
+		err_msg_ = str;
+#ifdef DEBUG
+		fprintf(stderr, "%s", str);
+#endif
+	}
+
+	FailedAssertionException(const FailedAssertionException&ex) : 
+	    DbstlException(ex)
+	{
+		err_msg_ = (char *)DbstlMalloc((u_int32_t)
+		    strlen(ex.err_msg_) + 1);
+		strcpy(err_msg_, ex.err_msg_);
+	}
+	virtual ~FailedAssertionException() throw()
+	{
+		free(err_msg_);
+	}
+};
+
+/// There is no such key in the database. The key can't not be passed into 
+/// the exception instance because this class has to be a class template for
+/// that to work.
+class _exported NoSuchKeyException : public DbstlException
+{
+public:
+	NoSuchKeyException() 
+	    : DbstlException("\nNo such key in the container.")
+	{
+	}
+
+	COPY_CONSTRUCTOR(NoSuchKeyException)
+};
+
+/// Some argument of a function is invalid.
+class _exported InvalidArgumentException : public DbstlException 
+{
+public:
+	explicit InvalidArgumentException(const char *errmsg) : 
+	    DbstlException(errmsg)
+	{
+#ifdef DEBUG
+		cerr<<errmsg;
+#endif
+	}
+
+	InvalidArgumentException(const char *argtype, const char *arg) : 
+	    DbstlException(argtype, arg, 0)
+	{
+#ifdef DEBUG
+		cerr<<"\nInvalid argument exception: "<<argtype<<"\t"<<arg;
+#endif
+	}
+
+	COPY_CONSTRUCTOR(InvalidArgumentException)
+};
+
+/// The function called is not supported in this class.
+class _exported NotSupportedException : public DbstlException 
+{
+public:
+	explicit NotSupportedException(const char *str) : DbstlException(str)
+	{
+	}
+
+	COPY_CONSTRUCTOR(NotSupportedException)
+};
+
+/// The function can not be called in this context or in current configurations.
+class _exported InvalidFunctionCall : public DbstlException 
+{
+public:
+	explicit InvalidFunctionCall(const char *str) : DbstlException(str)
+	{
+#ifdef DEBUG
+		cerr<<"\nInvalid function call: "<<str;
+#endif
+	}
+
+	COPY_CONSTRUCTOR(InvalidFunctionCall)
+};
+/** @}*/
+#undef COPY_CONSTRUCTOR
+END_NS
+
+#endif //_DB_STL_EXCEPTION_H
diff --git a/stl/dbstl_inner_utility.h b/stl/dbstl_inner_utility.h
new file mode 100644
index 0000000..fcf1431
--- /dev/null
+++ b/stl/dbstl_inner_utility.h
@@ -0,0 +1,59 @@
+/*-
+ * See the file LICENSE for redistribution information.
+ *
+ * Copyright (c) 2009 Oracle.  All rights reserved.
+ *
+ * $Id$
+ */
+
+#ifndef _DB_STL_GLOBAL_INNER_OBJECT_
+#define _DB_STL_GLOBAL_INNER_OBJECT_
+
+#include "dbstl_common.h"
+
+START_NS(dbstl)
+/* 
+ * This is the interface for all classes that has some global/singleton 
+ * instances that will survive during the entire process lifetime and 
+ * need to be deleted before process exit. Not deleting them won't make
+ * a difference because they have to be alive when the process is alive,
+ * they are not memory leaks. However, we will still delete them before
+ * process exit, to make no memory leak reports by memory leak checkers.
+ */
+class _exported DbstlGlobalInnerObject
+{
+public:
+	DbstlGlobalInnerObject(){}
+	virtual ~DbstlGlobalInnerObject(){}
+
+}; // DbstlGlobalInnerObject
+
+void _exported register_global_object(DbstlGlobalInnerObject *gio);
+
+// This class stores the pointer of an object allocated on heap, and when
+// an instance of this class is destructed, it deletes that object.
+// Any instance of this class can only be created on the heap so that we
+// can control when to destruct its instances. It derives from 
+// DbstlGlobalInnerObject so that we can register pointers to instances of
+// this class into ResourceManager, just like other objects which implements
+// the DbstlGlobalInnerObject interface. So the ultimate purpose for this
+// template is to manage objects which can't implement DbstlGlobalInnerObject
+// interface, like objects of Db, DbEnv, etc.
+//
+template<typename T>
+class _exported DbstlHeapObject : public DbstlGlobalInnerObject
+{
+private:
+	typedef DbstlHeapObject<T> self;
+	T *obj;
+
+	// Only allow creating to heap.
+	DbstlHeapObject(T *obj1) { obj = obj1; }
+public:
+	static self *instance(T *obj1) { return new self(obj1); }
+	virtual ~DbstlHeapObject() { delete obj; }
+}; // DbstlHeapObject
+
+END_NS
+#endif // !_DB_STL_GLOBAL_INNER_OBJECT_
+
diff --git a/stl/dbstl_map.h b/stl/dbstl_map.h
new file mode 100644
index 0000000..05d9ed0
--- /dev/null
+++ b/stl/dbstl_map.h
@@ -0,0 +1,3395 @@
+/*-
+ * See the file LICENSE for redistribution information.
+ *
+ * Copyright (c) 2009 Oracle.  All rights reserved.
+ *
+ * $Id$
+ */
+
+#ifndef _DB_STL_DB_MAP_H_
+#define _DB_STL_DB_MAP_H_
+
+#include <string>
+
+#include "dbstl_common.h"
+#include "dbstl_dbc.h"
+#include "dbstl_container.h"
+#include "dbstl_resource_manager.h"
+#include "dbstl_element_ref.h"
+#include "dbstl_base_iterator.h"
+
+START_NS(dbstl)
+
+using std::pair;
+using std::make_pair;
+using std::string;
+// Forward declarations, DO NOT delete the default argument values
+// because class templates defintions need them. No need for _export here.
+//
+template <Typename T>
+class _DB_STL_set_value;
+
+template <Typename kdt, Typename ddt, Typename value_type_sub = 
+    ElementRef<ddt> >
+class db_map_iterator;
+
+template <Typename kdt, Typename ddt, Typename value_type_sub = 
+    ElementRef<ddt>, Typename iterator_t = 
+    db_map_iterator<kdt, ddt, value_type_sub> >
+class db_map;
+
+template<Typename kdt, Typename ddt, Typename value_type_sub = 
+    ElementRef<ddt>, Typename iterator_t = 
+    db_map_iterator<kdt, ddt, value_type_sub> >
+class db_multimap;
+
+template <Typename kdt>
+class db_set_base_iterator;
+
+template <Typename kdt, Typename value_type_sub = ElementRef<kdt> >
+class db_set_iterator;
+
+template <Typename kdt, Typename value_type_sub = ElementRef<kdt> >
+class db_set;
+
+template <Typename kdt, Typename value_type_sub = ElementRef<kdt> >
+class db_multiset;
+
+/** \ingroup dbstl_iterators
+@{
+\defgroup db_map_iterators Iterator classes for db_map and db_multimap.
+db_map has two iterator class templates -- db_map_base_iterator and
+db_map_iterator. They are the const iterator class and iterator class for
+db_map and db_multimap. db_map_iterator inherits from db_map_base_iterator.
+
+The two classes have identical behaviors to std::map::const_iterator and
+std::map::iterator respectively. Note that the common public member function
+behaviors are described in the db_base_iterator section.
+
+The differences between the two classes are that the db_map_base_iterator can 
+only be used to read its referenced value, while db_map_iterator allows both 
+read and write access. If your access pattern is readonly, it is strongly 
+recommended that you use the const iterator because it is faster and more 
+efficient.
+@{
+*/
+//////////////////////////////////////////////////////////////////////
+// db_map_base_iterator class definition
+//
+// This class is a const iterator class for db_map and db_multimap, it can
+// be used only to read data under the iterator, can't be used to write.
+//
+// Iterator const-ness implementation:
+//
+// const iterators can not update key/data pairs, other than this, 
+// they can do anything else like non-const iterators, so we define
+// db_map_base_iterator to be the const iterator which can only be used
+// to read its underlying key/data pair, but not updating them; We 
+// derive the db_map_iterator from the base iterator to be the 
+// read-write iterator. We also maintain a "readonly" property in all
+// iterators so that users can specify a db_map_iterator to be
+// read only. db_map_base_iterator is more efficient to read data then
+// db_map_iterator, so read only accesses are strongly recommended to be 
+// done using a const iterator.
+//
+template <Typename kdt, Typename ddt, Typename csrddt = ddt>
+class _exported db_map_base_iterator : public 
+    db_base_iterator<ddt>
+{
+protected:
+	typedef db_map_base_iterator<kdt, ddt, csrddt> self;
+	typedef db_base_iterator<ddt> base;
+	using base::replace_current_key;
+public:
+	typedef kdt key_type;
+	typedef ddt data_type;
+	typedef pair<kdt, ddt> value_type;
+	// Not used in this class, but required to satisfy 
+	// db_reverse_iterator type extraction.
+	typedef ptrdiff_t difference_type;
+	typedef difference_type distance_type;
+	typedef value_type& reference;
+	typedef value_type* pointer;
+	typedef value_type value_type_wrap;
+	// We have to use standard iterator tags to match the parameter 
+	// list of stl internal functions, we can't use our own tag 
+	// classes, so we don't write tag classes in dbstl.
+	//
+	typedef std::bidirectional_iterator_tag iterator_category;
+
+	////////////////////////////////////////////////////////////////////
+	//
+	// Begin public constructors and destructor.
+	/// @name Constructors and destructor
+	/// Do not create iterators directly using these constructors, but
+	/// call db_map::begin or db_multimap_begin to get instances of
+	/// this class.
+	/// \sa db_map::begin() db_multimap::begin()
+	//@{
+	/// Copy constructor.
+	/// \param vi The other iterator of the same type to initialize this.
+	db_map_base_iterator(const self& vi)
+	    : db_base_iterator<ddt>(vi)
+	{
+		// Lazy-dup another cursor, cursor to iterator mapping 
+		// is 1 to 1.
+		pcsr_ = vi.pcsr_;
+		curpair_base_.first = vi.curpair_base_.first;
+		curpair_base_.second = vi.curpair_base_.second;
+	}
+
+	/// Base copy constructor.
+	/// \param vi Initialize from a base class iterator.
+	db_map_base_iterator(const base& vi) : base(vi), 
+	    pcsr_(new cursor_type(vi.get_bulk_retrieval(), 
+	    vi.is_rmw(), vi.is_directdb_get()))
+	{
+		
+	}
+	
+	/// Constructor.
+	/// \param powner The container which creates this iterator.
+	/// \param b_bulk_retrieval The bulk read buffer size. 0 means 
+	/// bulk read disabled.
+	/// \param rmw Whether set DB_RMW flag in underlying cursor.
+	/// \param directdbget Whether do direct database get rather than
+	/// using key/data values cached in the iterator whenever read.
+	/// \param readonly Whether open a read only cursor. Only effective 
+	/// when using Berkeley DB Concurrent Data Store.
+	explicit db_map_base_iterator(db_container*powner, 
+	    u_int32_t b_bulk_retrieval = 0, bool rmw = false, 
+	    bool directdbget = true, bool readonly = false)
+	    : db_base_iterator<ddt>(
+	    powner, directdbget, readonly, b_bulk_retrieval, rmw),
+	    pcsr_(new cursor_type(b_bulk_retrieval, rmw, directdbget)) 
+	{ 	
+	}
+
+	/// Default constructor, dose not create the cursor for now.
+	db_map_base_iterator()
+	{
+	}
+
+	// Use virtual because ElementRef<> uses a db_base_iterator* pointer
+	// to refer to the iterator, and also use "dead_" flag to avoid 
+	// multiple calls to the same destructor by ~ElementRef<>().
+	/// Destructor.
+	virtual ~db_map_base_iterator() 
+	{
+		this->dead_ = true;
+		if (pcsr_)
+			pcsr_->close();	
+	}
+	//@}
+
+	////////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////////
+	// Begin functions that shift iterator position.
+	//
+	// Do not throw exceptions here because it is likely and normal 
+	// to iterate to the "end itrerator". 
+	//
+	/// @name Iterator increment movement functions.
+	/// The two functions moves the iterator one element backward, so that
+	/// the element it sits on has a bigger key. The btree/hash key
+	/// comparison routine determines which key is greater.
+	/// Use ++iter rather than iter++ where possible to avoid two useless
+	/// iterator copy constructions.
+	//@{
+	/// Pre-increment.
+	/// \return This iterator after incremented.
+	inline self& operator++()
+	{
+		next();
+		
+		return *this;
+	}
+
+	/// Post-increment.
+	/// \return Another iterator having the old value of this iterator.
+	inline self operator++(int)
+	{
+		self itr = *this;
+
+		next();
+		
+		return itr;
+	}
+	//@}
+
+	/// @name Iterator decrement movement functions.
+	/// The two functions moves the iterator one element forward, so that
+	/// the element it sits on has a smaller key. The btree/hash key 
+	/// comparison routine determines which key is greater.
+	/// Use --iter rather than iter-- where possible to avoid two useless
+	/// iterator copy constructions.
+	//@{
+	/// Pre-decrement.
+	/// \return This iterator after decremented.
+	inline 	self& operator--() 
+	{
+		prev();
+		
+		return *this;
+	}
+
+	/// Post-decrement.
+	/// \return Another iterator having the old value of this iterator.
+	self operator--(int)
+	{
+		self itr = *this;
+		prev();
+		
+		return itr;
+	}
+	//@}
+
+	/// Assignment operator. This iterator will point to the same key/data
+	/// pair as itr, and have the same configurations as itr.
+	/// \param itr The right value of assignment.
+	/// \return The reference of itr.
+	/// \sa db_base_iterator::operator=(const self&)
+	// We will duplicate the Dbc cursor here.
+	inline const self& operator=(const self&itr) 
+	{
+		ASSIGNMENT_PREDCOND(itr)
+		base::operator=(itr);
+
+		curpair_base_.first = itr.curpair_base_.first;
+		curpair_base_.second = itr.curpair_base_.second;
+		if (pcsr_)
+			pcsr_->close();
+		pcsr_ = itr.pcsr_;
+		
+		return itr;
+	}
+
+	////////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////////
+	// Begin iterator comparison functions.
+	//
+	/// \name Compare operators.
+	/// Only equal comparison is supported.
+	//@{
+	/// Compare two iterators.
+	/// Two iterators compare equal when they are both invalid or 
+	/// both valid and underlying cursor compare equal(i.e. sitting on the
+	/// same key/data pair).
+	//
+	// Note that the iterator itr or this iterator may be an invalid
+	// one, i.e. its this->itr_status_ is INVALID_ITERATOR_POSITION. 
+	// We do not distinguish between end and rend iterators although
+	// we are able to do so, because they are never compared together.
+	/// Equal comparison operator.
+	/// \param itr The iterator to compare against.
+	/// \return Returns true if equal, false otherwise.
+	inline bool operator==(const self&itr) const
+	{
+		COMPARE_CHECK(itr)	
+		if (((itr.itr_status_ == this->itr_status_) && 
+		    (this->itr_status_ == INVALID_ITERATOR_POSITION)) ||
+		    ((itr.itr_status_ == this->itr_status_) && 
+		    (pcsr_->compare((itr.pcsr_.base_ptr())) == 0)))
+			return true;
+		return false;
+		
+	}
+
+	/// Unequal comparison operator.
+	/// \param itr The iterator to compare against.
+	/// \return Returns false if equal, true otherwise.
+	/// \sa bool operator==(const self&itr) const
+	inline bool operator!=(const self&itr) const 
+	{
+		return !(*this == itr) ;
+	}
+	//@}
+	////////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////////
+	// Begin functions that retrieve values from the iterator.
+	//
+	// curpair_base_ is always kept updated on iterator movement, but if 
+	// directdb_get_ is true, curpair_base_ is also updated here before 
+	// making use of the value it references.
+	// Even if this iterator is invalid, this call is allowed, the
+	// default value of type T is returned.
+	//
+	// Note that the returned reference can only be used to read data,
+	// can't be used to update data.
+	/// \name Functions that retrieve values from the iterator.
+	//@{
+	/// Dereference operator.
+	/// Return the reference to the cached data element, which is an 
+	/// pair<Key_type, T>. You can only read its referenced data via 
+	/// this iterator but can not update it.
+	/// \return Current data element reference object, i.e. ElementHolder
+	/// or ElementRef object.
+	inline reference operator*() const 
+	{
+		
+		if (this->directdb_get_) { 
+			csrddt d;
+			pcsr_->get_current_key_data(curpair_base_.first, d);
+			assign_second0(curpair_base_, d);
+		}
+		// Returning reference, no copy construction.
+		return curpair_base_;
+	}
+	 
+	// curpair_base_ is always kept updated on iterator movement, but if 
+	// directdb_get_ is true, curpair_base_ is also updated here before 
+	// making use of the value it references.
+	// Even if this iterator is invalid, this call is allowed, the
+	// default value of type T is returned.
+	//
+	// Note that the returned reference can only be used to read data,
+	// can't be used to update data.
+	/// Arrow operator.
+	/// Return the pointer to the cached data element, which is an 
+	/// pair<Key_type, T>. You can only read its referenced data via 
+	/// this iterator but can not update it.
+	/// \return Current data element reference object's address, i.e. 
+	/// address of ElementHolder or ElementRef object.
+	inline pointer operator->() const
+	{
+		
+		if (this->directdb_get_) {
+			csrddt d;
+			pcsr_->get_current_key_data(curpair_base_.first, d);
+			assign_second0(curpair_base_, d);
+		}
+
+		return &curpair_base_;
+	}
+	//@}
+	////////////////////////////////////////////////////////////////////
+		
+	////////////////////////////////////////////////////////////////////
+	// Begin dbstl specific functions.
+	//
+	// Refresh the underlying cursor's current data and this object's 
+	// curpair_base_. It need to be called only if directdb_get is 
+	// disabled, and other iterators updated
+	// the key/data pair this iterator points to and we are about to use 
+	// this iterator to access that key/data pair. 
+	// If direct db get is enabled, this method never needs to be called.
+	/// @name dbstl specific functions
+	//@{
+	/// \brief Refresh iterator cached value.
+	/// \param from_db If not doing direct database get and this parameter
+	/// is true, we will retrieve data directly from db.
+	/// \sa db_base_iterator::refresh(bool) 
+	virtual int refresh(bool from_db = true) const
+	{
+		csrddt d;
+
+		if (from_db && !this->directdb_get_)
+			pcsr_->update_current_key_data_from_db(
+			    DbCursorBase::SKIP_NONE);
+		pcsr_->get_current_key_data(curpair_base_.first, d);
+		assign_second0(curpair_base_, d);
+
+		return 0;
+	}
+
+	// By calling this function, users can choose to close the underlying 
+	// cursor before iterator destruction to get better performance 
+	// potentially.
+	/// \brief Close underlying Berkeley DB cursor of this iterator.
+	/// \sa db_base_iterator::close_cursor() const
+	inline void close_cursor() const
+	{
+		if (pcsr_)
+			pcsr_->close();
+	}
+
+	/// Iterator movement function.
+	/// Move this iterator to the specified key k, by default moves
+	/// exactly to k, and update cached data element, you can
+	/// also specify DB_SET_RANGE, to move to the biggest key smaller 
+	/// than k. The btree/hash key comparison routine determines which
+	/// key is bigger. When the iterator is on a multiple container, 
+	/// move_to will move itself to the first key/data pair of the 
+	/// identical keys.
+	/// \param k The target key value to move to.
+	/// \param flag Flags available: DB_SET(default) or DB_SET_RANGE.
+	/// DB_SET will move this iterator exactly at k; DB_SET_RANGE moves
+	/// this iterator to k or the smallest key greater than k. If fail
+	/// to find such a key, this iterator will become invalid.
+	/// \return 0 if succeed; non-0 otherwise, and this iterator becomes
+	/// invalid. Call db_strerror with the return value to get the error 
+	/// message.
+	inline int move_to(const kdt& k, int flag = DB_SET) const
+	{
+		int ret;
+		// Use tmpk2 to avoid k being modified.
+		kdt tmpk2 = k;
+
+		this->itr_status_ = (ret = pcsr_->move_to(tmpk2, flag));
+		if (ret != 0) {
+			this->inval_pos_type_ = base::IPT_UNSET;
+			return ret;
+		}
+
+		refresh();
+
+		return ret;
+	}
+
+	/// Modify bulk buffer size. 
+	/// Bulk read is enabled when creating an
+	/// iterator, so users later can only modify the bulk buffer size
+	/// to another value, but can't enable/disable bulk read while an
+	/// iterator is already alive. 
+	/// \param sz The new size of the bulk read buffer of this iterator.
+	/// \return Returns true if succeeded, false otherwise.
+	/// \sa db_base_iterator::set_bulk_buffer(u_int32_t )
+	bool set_bulk_buffer(u_int32_t sz)
+	{
+		bool ret = this->pcsr_->set_bulk_buffer(sz);
+		if (ret)
+			this->bulk_retrieval_ = 
+			    this->pcsr_->get_bulk_bufsize();
+		return ret;
+	}
+
+	/// \brief Get bulk retrieval buffer size in bytes.
+	/// \return Return current bulk buffer size or 0 if bulk retrieval is
+	/// not enabled.
+	/// \sa db_base_iterator::get_bulk_bufsize()
+	u_int32_t get_bulk_bufsize()
+	{
+		this->bulk_retrieval_ = pcsr_->get_bulk_bufsize();
+		return this->bulk_retrieval_;
+	}
+	//@}
+	////////////////////////////////////////////////////////////////////
+
+protected:
+	
+	// The cursor_type is used to directly return the pair object, 
+	// rather than a reference to it
+	typedef DbCursor<kdt, csrddt> cursor_type;
+
+	friend class db_map_iterator<kdt, ddt, ElementRef<ddt> >;
+	friend class db_map_iterator<kdt, ddt, ElementHolder<ddt> >;
+	// Use friend classes to hide internal members from users.
+	friend class db_map<kdt, ddt, ElementHolder<ddt> >;
+	friend class db_map<kdt, ddt, ElementHolder<kdt>, 
+	    db_set_iterator<kdt, ElementHolder<kdt> > >;
+	friend class db_map<kdt, _DB_STL_set_value<kdt>, ElementHolder<kdt>, 
+	    db_set_iterator<kdt, ElementHolder<kdt> > >;
+
+	friend class db_set<kdt, ElementHolder<kdt> >;
+	friend class db_set_iterator<kdt, ElementHolder<kdt> >;
+	friend class db_multiset<kdt, ElementHolder<kdt> >;
+	friend class db_multimap<kdt, ddt, ElementHolder<ddt> >;
+	friend class db_multimap<kdt, _DB_STL_set_value<kdt>, 
+	    ElementHolder<kdt>, db_set_iterator<kdt, ElementHolder<kdt> > >;
+
+	friend class db_map<kdt, ddt, ElementRef<ddt> >;
+	friend class db_map<kdt, _DB_STL_set_value<kdt>, ElementRef<kdt>, 
+	    db_set_iterator<kdt, ElementRef<kdt> > >;
+
+	friend class db_set<kdt, ElementRef<kdt> >;
+	friend class db_set_iterator<kdt, ElementRef<kdt> >;
+	friend class db_multiset<kdt, ElementRef<kdt> >;
+	friend class db_multimap<kdt, ddt, ElementRef<ddt> >;
+	friend class db_multimap<kdt, _DB_STL_set_value<kdt>, ElementRef<kdt>,
+	    db_set_iterator<kdt, ElementRef<kdt> > >;
+
+
+	////////////////////////////////////////////////////////////////////
+	// Begin db_map_base_iterator data members.
+	//
+	// Cursor of this iterator, note that each db_map_base_iterator has a  
+	// unique DbCursor, not shared with any other iterator, and when copy 
+	// constructing or assigning, the cursor is duplicated
+	// when it is actually used to access db.
+	//
+	mutable LazyDupCursor<DbCursor<kdt, csrddt> > pcsr_;
+
+	// In order for std::map style itrerator to work, we need a pair 
+	// here to store the key-value pair this iterator currently points
+	// to in the db_map. 
+	//
+	// curpair_base_ is always kept updated on every cursor/iterator 
+	// movement and initialized to point to the first key-value pair when
+	// db_map<>::begin() is called.
+	//
+	mutable value_type curpair_base_;	
+	////////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////////
+	// Begin internal helper functions.
+	//
+	// Open the iterator and its cursor.
+	//
+	void open() const
+	{	
+		u_int32_t oflags = 0, coflags = 0;
+		int ret;
+		Db *pdb = this->owner_->get_db_handle();
+		DbEnv *penv = pdb->get_env();
+
+		coflags = this->owner_->get_cursor_open_flags();
+		assert(this->owner_ != NULL);
+		if (!this->read_only_ && penv != NULL) {
+			BDBOP((penv->get_open_flags(&oflags)), ret);
+			if ((oflags & DB_INIT_CDB) != 0)
+				this->owner_->set_cursor_open_flags(coflags |= 
+				    DB_WRITECURSOR);
+		}
+		if (!pcsr_)
+			pcsr_.set_cursor(new DbCursor<kdt, csrddt>(
+			    this->bulk_retrieval_, 
+			    this->rmw_csr_, this->directdb_get_));
+		this->itr_status_ = pcsr_->open((db_container*)this->owner_, 
+		    coflags);
+		
+	}
+
+	// Move this iterator as well as the underlying Dbc* cursor to 
+	// first element and update cur_pair_.
+	//
+	int first() const
+	{
+
+		assert(this->owner_ != NULL);
+		this->itr_status_ = pcsr_->first();
+		if (this->itr_status_ == 0)	
+			refresh();
+		else
+			this->inval_pos_type_ = base::IPT_UNSET;
+
+		return this->itr_status_;
+		
+	}
+
+	// Move this iterator as well as the underlying Dbc* cursor
+	// to last effective(valid) element and update cur_pair_.
+	//
+	int last() const
+	{
+
+		assert(this->owner_ != NULL);
+		this->itr_status_ = pcsr_->last();
+		if (this->itr_status_ == 0)
+			refresh();
+		else
+			this->inval_pos_type_ = base::IPT_UNSET;
+
+		return this->itr_status_;
+	}
+
+	// Move this iterator as well as the underlying Dbc* cursor
+	// to next element, then update its position flags and cur_pair_.
+	//
+	int next(int flags = DB_NEXT) const
+	{
+
+		assert(this->owner_ != NULL);
+		
+		if (this->itr_status_ == INVALID_ITERATOR_POSITION) {
+			if (this->inval_pos_type_ == base::IPT_BEFORE_FIRST) {
+				// This rend itr must have an non-NULL owner.
+				open();
+				// rend itr can go back to first element.
+				this->itr_status_ = first();
+			} else if (this->inval_pos_type_ == base::IPT_UNSET) {
+				THROW0(InvalidIteratorException);
+			}
+			// Else, return itr_status_ in last line.
+		} else {
+			
+			this->itr_status_ = pcsr_->next(flags);
+			if (this->itr_status_ == 0)
+				refresh();
+			else 
+				this->inval_pos_type_ = base::IPT_AFTER_LAST;
+			
+		}
+		
+		return this->itr_status_;
+	}
+
+	// Move this iterator as well as the underlying Dbc* cursor
+	// to previous element.
+	//
+	int prev(int flags = DB_PREV) const
+	{
+
+		assert(this->owner_ != NULL);
+		if (this->itr_status_ == INVALID_ITERATOR_POSITION) { 
+			if (this->inval_pos_type_ == base::IPT_AFTER_LAST) {
+				// This rend itr must have an non-NULL owner.
+				open();
+				// end itr can go back to last element.
+				this->itr_status_ = last();
+			} else if (this->inval_pos_type_ == base::IPT_UNSET) {
+				THROW0(InvalidIteratorException);
+			}
+			// Else, return itr stat in last line.
+		} else {
+			this->itr_status_ = pcsr_->prev(flags);
+			if (this->itr_status_ == 0)
+				refresh();
+			else 
+				this->inval_pos_type_ = base::IPT_BEFORE_FIRST;
+			
+		}
+
+		return this->itr_status_;
+	}
+
+	void set_curpair_base(const kdt& k, const csrddt &d) const
+	{
+		curpair_base_.first = k;
+		assign_second0(curpair_base_, d);
+	}
+
+	////////////////////////////////////////////////////////////////////
+
+protected: // Do not remove this line, otherwise assign_second0 may be public.
+#ifndef DOXYGEN_CANNOT_SEE_THIS
+#if NO_MEMBER_FUNCTION_PARTIAL_SPECIALIZATION
+};// end of db_map_base_iterator<>
+template <Typename kdt, Typename datadt, Typename ddt>
+void assign_second0(pair<kdt, ddt>& v, const datadt& d) 
+{
+	v.second = d;
+}
+
+template<Typename kdt, Typename ddt>
+void assign_second0(pair<kdt, ddt> &v, 
+    const _DB_STL_set_value<kdt>&
+    /* d unused, use v.first to assign v.second */) 
+{
+	v.second = v.first;
+}
+#else
+
+template <Typename datadt>
+inline void assign_second0(value_type& v, const datadt& d) const
+{
+	v.second = d;
+}
+
+template<>
+inline void 
+assign_second0(value_type &v, const _DB_STL_set_value<kdt>& 
+    /* d unused, use v.first to assign v.second */) const
+{
+	v.second = v.first;
+}
+
+};// end of db_map_base_iterator<>
+
+#endif
+
+#else
+};
+#endif // DOXYGEN_CANNOT_SEE_THIS
+//@} // db_map_iterators
+//@} // dbstl_iterators
+
+
+#if NO_MEMBER_FUNCTION_PARTIAL_SPECIALIZATION
+template <Typename kdt, Typename datadt, Typename value_type_sub>
+void assign_second0(pair<kdt, value_type_sub>& v, const datadt& d) ;
+#endif
+
+//////////////////////////////////////////////////////////////////////////
+//////////////////////////////////////////////////////////////////////////
+//
+// db_map_iterator class template definition
+//
+// db_map_iterator is the iterator class template for db_map and 
+// db_multimap, it is also the base class for db_set_iterator. It can be
+// used to both read and write the database.
+//
+// Template parameters info:
+// kdt is "key data type", ddt is "data data type", value_type_sub is
+// either ElementRef<ddt> (by default, in this case ElementRef inherits
+// from ddt, so ddt must not be a primitive type) or ElementHolder<ddt>,
+// in this case ElementHolder has a data member of type ddt, so suitable for
+// primitive types, but don't apply it to classes otherwise you can't access
+// members like this : *iterator.member = value.  
+//
+/// \ingroup dbstl_iterators 
+//@{
+/// \ingroup db_map_iterators
+//@{
+template <Typename kdt, Typename ddt, Typename value_type_sub>
+class _exported db_map_iterator : public 
+    db_map_base_iterator<kdt, typename value_type_sub::content_type, ddt>
+{
+protected:
+	typedef db_map_iterator<kdt, ddt, value_type_sub> self;
+	typedef typename value_type_sub::content_type realddt;
+	using db_base_iterator<typename value_type_sub::content_type>::
+	    replace_current_key;
+public:
+	typedef kdt key_type;
+	typedef ddt data_type;
+	typedef pair<kdt, ddt> value_type;
+	typedef pair<kdt, value_type_sub> value_type_wrap;
+	// Not used in this class, but required to satisfy 
+	// db_reverse_iterator type extraction.
+	typedef ptrdiff_t difference_type;
+	typedef difference_type distance_type;
+	typedef value_type_wrap& reference;
+	typedef value_type_wrap* pointer;
+
+	// We have to use standard iterator tags to match the parameter 
+	// list of stl internal functions, we can't use our own tag 
+	// classes, so we don't write tag classes in dbstl.
+	//
+	typedef std::bidirectional_iterator_tag iterator_category;
+	
+	// Refresh the underlying cursor's current data and this object's 
+	// curpair_. It need to be called only if other iterators updated the 
+	// key/data pair this iterator points to and we are about to use 
+	// this iterator to access that key/data pair. If direct db get is
+	// enabled, this method never needs to be called.
+	/// \brief Refresh iterator cached value.
+	/// \param from_db If not doing direct database get and this parameter
+	/// is true, we will retrieve data directly from db.
+	/// \sa db_base_iterator::refresh(bool )
+	virtual int refresh(bool from_db = true) const
+	{
+		kdt k;
+		ddt d;
+
+		if (from_db && !this->directdb_get_)
+			this->pcsr_->update_current_key_data_from_db(
+			    DbCursorBase::SKIP_NONE);
+		this->pcsr_->get_current_key_data(k, d);
+		curpair_.first = k;
+		assign_second(curpair_, d);
+		this->set_curpair_base(k, d);
+
+		return 0;
+	}
+
+	////////////////////////////////////////////////////////////////
+	// Begin constructors and destructor definitions.
+	/// \name Constructors and destructor
+	/// Do not create iterators directly using these constructors, but
+	/// call db_map::begin or db_multimap_begin to get instances of
+	/// this class.
+	/// \sa db_map::begin() db_multimap::begin()
+	//@{
+	/// Copy constructor.
+	/// \param vi The other iterator of the same type to initialize this.
+	db_map_iterator(const db_map_iterator<kdt, ddt, value_type_sub>& vi)
+	    : db_map_base_iterator<kdt, realddt, ddt>(vi)
+	{
+		// Lazy-dup another cursor, cursor to iterator mapping 
+		// is 1 to 1.
+		curpair_.first = vi.curpair_.first;
+		curpair_.second._DB_STL_CopyData(vi.curpair_.second);
+		curpair_.second._DB_STL_SetIterator(this);
+	}
+
+	/// Base copy constructor.
+	/// \param vi Initialize from a base class iterator.
+	db_map_iterator(const db_map_base_iterator<kdt, realddt, ddt>& vi) :
+	    db_map_base_iterator<kdt, realddt, ddt>(vi)
+
+	{
+		curpair_.second._DB_STL_SetIterator(this);
+		curpair_.first = vi->first;
+		curpair_.second._DB_STL_CopyData(vi->second);
+	}
+
+	/// Constructor.
+	/// \param powner The container which creates this iterator.
+	/// \param b_bulk_retrieval The bulk read buffer size. 0 means 
+	/// bulk read disabled.
+	/// \param brmw Whether set DB_RMW flag in underlying cursor.
+	/// \param directdbget Whether do direct database get rather than
+	/// using key/data values cached in the iterator whenever read.
+	/// \param b_read_only Whether open a read only cursor. Only effective
+	/// when using Berkeley DB Concurrent Data Store.
+	explicit db_map_iterator(db_container*powner, 
+	    u_int32_t b_bulk_retrieval = 0, bool brmw = false, 
+	    bool directdbget = true, bool b_read_only = false)
+	    : db_map_base_iterator<kdt, realddt, ddt>
+	    (powner, b_bulk_retrieval, brmw, directdbget, b_read_only) 
+	{ 
+		curpair_.second._DB_STL_SetIterator(this);
+	}
+
+	/// Default constructor, dose not create the cursor for now.
+	db_map_iterator() : db_map_base_iterator<kdt, realddt, ddt>()
+	{
+		curpair_.second._DB_STL_SetIterator(this);
+	}
+
+	// Use virtual because ElementRef<> uses a db_base_iterator* pointer 
+	// to refer to the iterator, and also use "dead_" flag to avoid 
+	// multiple call to the same destructor by ~ElementRef<>().
+	/// Destructor.
+	virtual ~db_map_iterator() 
+	{
+		// Required here though set in base destructor too.
+		this->dead_ = true;
+	}
+	//@}
+	////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////////
+	// Begin functions that shift iterator position.
+	//
+	// Do not throw exceptions here because it is likely and normal 
+	// to iterate to the "end itrerator". 
+	/// \name Iterator movement operators.
+	//@{
+	/// Pre-increment \sa db_map_base_iterator::operator++()
+	/// \return This iterator after incremented.
+	inline self& operator++()
+	{
+		this->next();
+		
+		return *this;
+	}
+
+	/// Post-increment \sa db_map_base_iterator::operator++(int)
+	/// \return Another iterator having the old value of this iterator.
+	inline self operator++(int)
+	{
+		self itr = *this;
+
+		this->next();
+		
+		return itr;
+	}
+
+	/// Pre-decrement \sa db_map_base_iterator::operator--()
+	/// \return This iterator after decremented.
+	inline 	self& operator--() 
+	{
+		this->prev();
+		
+		return *this;
+	}
+
+	/// Post-decrement \sa db_map_base_iterator::operator--(int)
+	/// \return Another iterator having the old value of this iterator.
+	self operator--(int)
+	{
+		self itr = *this;
+		this->prev();
+		
+		return itr;
+	}
+	//@}
+	// Assignment operator, we will duplicate the Dbc cursor here.
+	/// Assignment operator. This iterator will point to the same key/data
+	/// pair as itr, and have the same configurations as itr.
+	/// \param itr The right value of assignment.
+	/// \return The reference of itr.
+	/// \sa db_base_iterator::operator=(const self&)
+	inline const self& operator=(const self&itr) 
+	{
+		ASSIGNMENT_PREDCOND(itr)
+		base::operator=(itr);
+
+		curpair_.first = itr.curpair_.first;
+
+		// Only copy data from itr.curpair_ into curpair_, 
+		// don't store into db. Note that we can not assign 
+		// itr.curpair_ to curpair_ simply by curpair_ = itr.curpair_,
+		// otherwise, ElementRef<>::operator= is called, which will
+		// update the data element referenced by this iterator.
+		//
+		curpair_.second._DB_STL_CopyData(itr.curpair_.second);
+		
+		return itr;
+	}
+	////////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////////
+	// Begin functions that retrieve values from the iterator.
+	//
+	// curpair_base_ is always kept updated on iterator movement, but if 
+	// directdb_get_ is true, curpair_base_ is also updated here before 
+	// making use of the value it references.
+	// Even if this iterator is invalid, this call is allowed, the
+	// default value of type T is returned.
+	//
+	/// \name Functions that retrieve values from the iterator.
+	//@{
+	/// Dereference operator.
+	/// Return the reference to the cached data element, which is an
+	/// pair<Key_type, ElementRef<T> > object if T is a class type or an
+	/// pair<Key_type, ElementHolder<T> > object if T is a C++ primitive
+	/// data type. 
+	/// \return Current data element reference object, i.e. ElementHolder
+	/// or ElementRef object.
+	inline reference operator*() const 
+	{
+		
+		if (this->directdb_get_) {
+			ddt d;
+			this->pcsr_->get_current_key_data(curpair_.first, d);
+			assign_second(curpair_, d);
+		}
+
+		return curpair_;// returning reference, no copy construction
+	}
+	 
+	// curpair_base_ is always kept updated on iterator movement, but if 
+	// directdb_get_ is true, curpair_base_ is also updated here before 
+	// making use of the value it references.
+	// Even if this iterator is invalid, this call is allowed, the
+	// default value of type T is returned.
+	/// Arrow operator.
+	/// Return the pointer to the cached data element, which is an
+	/// pair<Key_type, ElementRef<T> > object if T is a class type or an
+	/// pair<Key_type, ElementHolder<T> > object if T is a C++ primitive
+	/// data type. 
+	/// \return Current data element reference object's address, i.e. 
+	/// address of ElementHolder or ElementRef object.
+	inline pointer operator->() const
+	{
+	
+		if (this->directdb_get_) {
+			ddt d;
+			this->pcsr_->get_current_key_data(curpair_.first, d);
+			assign_second(curpair_, d);
+		}
+		return &curpair_;
+	}
+	//@}
+	////////////////////////////////////////////////////////////////////
+
+//@} // db_map_iterators
+//@} // dbstl_iterators
+protected:
+	// The cursor_type is used to directly return the pair object, 
+	// rather than a reference to it.
+	typedef DbCursor<kdt, ddt> cursor_type;
+	typedef db_map_base_iterator<kdt, realddt, ddt> base;
+	typedef db_map_base_iterator<kdt, realddt> const_version;
+
+	// Use friend classes to hide internal members from users.
+	friend class db_map<kdt, ddt, value_type_sub>;
+	friend class db_map<kdt, ddt, value_type_sub, 
+	    db_set_iterator<kdt, value_type_sub> >;
+	friend class db_set<kdt, value_type_sub>;
+	friend class db_set_iterator<kdt, value_type_sub>;
+	friend class db_multiset<kdt, value_type_sub>;
+	friend class db_multimap<kdt, ddt, value_type_sub>;
+	friend class db_multimap<kdt, _DB_STL_set_value<kdt>, value_type_sub,
+	    db_set_iterator<kdt, value_type_sub > >;
+
+	////////////////////////////////////////////////////////////////
+	// Begin db_map_iterator data members.
+	//
+	// In order for std::map style itrerator to work, we need a pair 
+	// here to store the key-value pair this iterator currently points
+	// to in the db_map. 
+	//
+	// curpair_ is always kept updated on every cursor/iterator movement
+	// and initialized to point to the first key-value pair when
+	// db_map<>::begin() is called.
+	//
+	mutable value_type_wrap curpair_;	
+	////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////
+	// Begin internal helper functions.
+	//
+	// Called by ElementRef<> object when this iterator belongs to the 
+	// object---The only situation is in db_container::operator[] which
+	// has to return an ElementRef/Holder object A, and its iterator has
+	// to survive until A is destructed.
+	virtual void delete_me() const
+	{
+		if (!this->dead_)
+			delete this;
+	}
+
+	// Duplicate this iterator.
+	virtual self* dup_itr() const
+	{
+		self *itr = new self(*this);
+		// The curpair_ of itr does not delete itr, the independent 
+		// one does.
+		//itr->curpair_.second._DB_STL_SetDelItr();
+		return itr;
+	}
+
+	// Replace the current key/data pair's data pointed to by this 
+	// iterator's underlying Dbc* cursor with the parameter d.
+	//
+	virtual int replace_current(
+	    const typename value_type_sub::content_type& d)
+	{
+		int ret;
+
+		if (this->read_only_) {
+			THROW(InvalidFunctionCall, (
+"db_map_iterator<>::replace_current can't be called via a read only iterator"));
+		}
+		ret = this->pcsr_->replace(d);
+		
+		return ret;
+	}
+
+	// Used by set iterator to store another different key : 
+	// remove the previous one then insert the new one.
+	// It has to be defined in this class because db_set_iterator
+	// inherits from db_map_iterator but we have no polymorphism when
+	// using stl because the object are always used rather the 
+	// pointer/reference.
+	//
+	virtual int replace_current_key(const kdt& k)
+	{
+		int ret;
+
+		if (this->read_only_) {
+			THROW(InvalidFunctionCall, (
+"db_map_iterator<>::replace_current_key can't be called via a read only iterator"));
+		}
+		ret = this->pcsr_->replace_key(k);
+
+		return ret;
+	}
+
+	////////////////////////////////////////////////////////////////
+
+
+protected: // Do not remove this line, otherwise assign_second may be public.
+#ifndef DOXYGEN_CANNOT_SEE_THIS
+#if NO_MEMBER_FUNCTION_PARTIAL_SPECIALIZATION
+};// end of db_map_iterator<>
+
+template <Typename kdt, Typename datadt, Typename value_type_sub>
+void assign_second(pair<kdt, value_type_sub>& v, const datadt& d) 
+{
+	v.second._DB_STL_CopyData(d);
+}
+
+template<Typename kdt, Typename value_type_sub>
+void assign_second(pair<kdt, value_type_sub> &v, 
+    const _DB_STL_set_value<kdt>&
+    /* d unused, use v.first to assign v.second */) 
+{
+	v.second._DB_STL_CopyData(v.first);
+}
+#else
+
+template <Typename datadt>
+inline void assign_second(value_type_wrap& v, const datadt& d) const
+{
+	v.second._DB_STL_CopyData(d);
+}
+
+template<>
+inline void 
+assign_second(value_type_wrap &v, const _DB_STL_set_value<kdt>& 
+    /* d unused, use v.first to assign v.second */) const
+{
+	v.second._DB_STL_CopyData(v.first);
+}
+
+};// end of db_map_iterator<>
+
+#endif
+#else
+};
+#endif // DOXYGEN_CANNOT_SEE_THIS
+u_int32_t hash_default(Db *dbp, const void *key, u_int32_t len);
+
+//////////////////////////////////////////////////////////////////////////
+/////////////////////////////////////////////////////////////////////////
+//
+// db_map container class definition
+/// \ingroup dbstl_containers
+//@{
+/// db_map has identical methods to std::map and the semantics for each
+/// method is identical to its std::map counterpart, except that it stores data
+/// into underlying Berkeley DB btree or hash database. Passing a database
+/// handle of btree or hash type creates a db_map equivalent to std::map and
+/// std::hashmap respectively.
+/// Database(dbp) and environment(penv) handle requirement(applies to all 
+/// constructors in this class template):
+/// 0. The dbp is opened inside the penv environment. Either one of the two 
+/// handles can be NULL. If dbp is NULL, an anonymous database is created 
+/// by dbstl. 
+/// 1. Database type of dbp should be DB_BTREE or DB_HASH.
+/// 2. No DB_DUP or DB_DUPSORT flag set in dbp.
+/// 3. No DB_RECNUM flag set in dbp.
+/// 4. No DB_TRUNCATE specified in dbp's database open flags.
+/// 5. DB_THREAD must be set if you are sharing the dbp across 
+/// multiple threads directly, or indirectly by sharing the container object 
+/// across multiple threads.
+/// \param kdt The key data type.
+/// \param ddt The data data type. db_map stores key/data pairs.
+/// \param value_type_sub Do not specify anything if ddt type is a 
+/// class/struct type; Otherwise, specify ElementHolder<ddt> to it.
+/// \param iterator_t Never specify anything to this type parameter. It is
+/// only used internally.
+/// \sa db_container db_container(Db*, DbEnv*) db_container(const db_container&)
+template <Typename kdt, Typename ddt, Typename value_type_sub, 
+    Typename iterator_t>
+class _exported db_map : public db_container 
+{
+
+public:
+	// iterator_t is default argument, see forward declaration at the
+	// head of this file
+	typedef iterator_t iterator;
+	typedef typename iterator::const_version const_iterator;
+	typedef db_reverse_iterator<iterator, const_iterator> reverse_iterator;
+	typedef db_reverse_iterator<const_iterator, iterator>
+		const_reverse_iterator;
+	typedef kdt key_type;
+	typedef ddt data_type;
+	typedef value_type_sub data_type_wrap;
+	typedef pair<kdt, ddt> value_type;
+	typedef pair<kdt, value_type_sub> value_type_wrap;
+	typedef const value_type const_value_type;
+	typedef ptrdiff_t difference_type;
+	typedef size_t size_type;
+	// The following three types are not used in db_map, but we define
+	// them to conform to stl specifications.
+	typedef value_type_wrap& reference;
+	typedef const value_type& const_reference;
+	typedef value_type_wrap* pointer;
+protected:
+	typedef db_map<kdt, ddt, value_type_sub, iterator> self;
+	typedef typename value_type_sub::content_type realddt;
+
+	// This constructor is for db_multimap's constructors to call, 
+	// because other constructors of this class will verify db handles 
+	// and create one if needed. We need a special one that don't do 
+	// anything. The BulkRetrievalOption is randomly picked, no special
+	// implications at all.
+	db_map(BulkRetrievalOption& arg){ delete &arg; }
+public:
+	////////////////////////////////////////////////////////////////
+	// Begin inner class definitions.
+	//
+	// key_compare class definition, it is defined as an inner class,
+	// using underlying btree/hash db's compare function
+	//
+	class key_compare 
+	{
+	private:
+		Db*pdb;
+	public:
+		key_compare(Db*pdb1)
+		{
+			pdb = pdb1;
+		}
+		bool operator()(const kdt& k1, const kdt& k2) const
+		{
+			return compare_keys(pdb, k1, k2);
+		}
+
+	}; // key_compare class definition
+
+	// value_compare class definition, it is defined as an inner class,
+	// using key_compare class to do comparison. 
+	//
+	// The difference between key_compare and value_compare is the 
+	// parameter its operator() function accepts, see the function
+	// signature.
+	//
+	class value_compare 
+	{
+		key_compare kc;
+	public:
+		value_compare(Db*pdb) : kc(pdb)
+		{
+		
+		}
+
+		bool operator()(const value_type& v1, 
+		    const value_type& v2) const
+		{
+			
+			return kc(v1.first, v2.first);
+		}
+
+	}; // value_compare class definition
+
+	class hasher
+	{
+	private:
+		Db*pdb;
+	public:
+		hasher(Db*db){pdb = db;}
+		size_t operator()(const kdt&k) const
+		{
+			DBTYPE dbtype;
+			int ret;
+
+			assert(pdb != NULL);
+			ret = pdb->get_type(&dbtype);
+			assert(ret == 0);
+			if (dbtype != DB_HASH) {
+				THROW(InvalidFunctionCall, (
+				    "db_map<>::hasher"));
+			}
+			h_hash_fcn_t hash = NULL;
+			BDBOP(pdb->get_h_hash(&hash), ret);
+			if (hash == NULL)
+				hash = hash_default;
+			return hash(pdb, &k, sizeof(k));
+		}
+	}; // hasher
+
+	class key_equal
+	{
+	private:
+		Db*pdb;
+	public:
+		key_equal(Db*db){pdb = db;}
+		bool operator()(const kdt& kk1, const kdt&kk2) const
+		{
+			DBTYPE dbtype;
+			kdt k1 = kk1, k2 = kk2;
+			int ret;
+
+			dbstl_assert(pdb != NULL);
+			ret = pdb->get_type(&dbtype);
+			dbstl_assert(ret == 0);
+			if (dbtype != DB_HASH) {
+				THROW(InvalidFunctionCall, (
+				    "db_map<>::key_equal"));
+			}
+
+			db_compare_fcn_t comp = NULL;
+			BDBOP(pdb->get_h_compare(&comp), ret);
+			if (comp == NULL)
+				return memcmp(&kk1, &kk2, sizeof(kdt)) == 0;
+			Dbt kd1(&k1, sizeof(k1)), kd2(&k2, sizeof(k2));
+			
+			return comp(pdb, &kd1, &kd2) == 0;
+
+
+		}
+
+	};// key_equal
+	////////////////////////////////////////////////////////////////
+
+	/// Function to get key compare functor.
+	/// Used when this container is a hash_map, hash_multimap,
+	/// hash_set or hash_multiset equivalent.
+	/// \return key_equal type of compare functor.
+	/// \sa http://www.sgi.com/tech/stl/hash_map.html
+	inline key_equal key_eq() const
+	{
+		key_equal ke(this->get_db_handle());
+		return ke;
+	}
+
+	/// Function to get hash key generating functor.
+	/// Used when this container is a hash_map, hash_multimap,
+	/// hash_set or hash_multiset equivalent.
+	/// \return The hash key generating functor.
+	/// \sa http://www.sgi.com/tech/stl/hash_map.html
+	inline hasher hash_funct() const
+	{
+		hasher h(this->get_db_handle());
+		return h;
+
+	}
+
+	/// Function to get value compare functor. Used when this container
+	/// is a std::map, std::multimap, std::set or std::multiset equivalent.
+	/// \return The value compare functor.
+	/// \sa http://www.cplusplus.com/reference/stl/map/value_comp/
+	inline value_compare value_comp() const
+	{
+		value_compare vc(this->get_db_handle());
+		return vc;
+	}
+	
+	/// Function to get key compare functor. Used when this container
+	/// is a std::map, std::multimap, std::set or std::multiset equivalent.
+	/// \return The key compare functor.
+	/// \sa http://www.cplusplus.com/reference/stl/map/key_comp/
+	inline key_compare key_comp() const 
+	{
+		key_compare kc(this->get_db_handle());
+		return kc;
+	}
+
+	////////////////////////////////////////////////////////////////
+	// Begin constructors and destructor definitions.
+	/// \name Constructors and destructor
+	//@{
+	// We don't need the equal compare or allocator here, user need to 
+	// call Db::set_bt_compare or Db::set_h_compare to set comparison
+	// function.
+	/// Create a std::map/hash_map equivalent associative container.
+	/// See the handle requirement in class details to pass correct 
+	/// database/environment handles.
+	/// \param dbp The database handle.
+	/// \param envp The database environment handle.
+	/// \sa db_container(Db*, DbEnv*)
+	explicit db_map(Db *dbp = NULL, DbEnv* envp = NULL)  : 
+	    db_container(dbp, envp)
+	{
+		const char *errmsg;
+
+		this->open_db_handles(dbp, envp, DB_BTREE, 
+		    DB_CREATE | DB_THREAD, 0);
+		
+		if ((errmsg = verify_config(dbp, envp)) != NULL) {
+			THROW(InvalidArgumentException, ("Db*", errmsg));
+		}
+		this->set_db_handle_int(dbp, envp);
+	}
+
+	/// Iteration constructor. Iterates between first and last, 
+	/// setting a copy of each of the sequence of elements as the
+	/// content of the container object. 
+	/// Create a std::map/hash_map equivalent associative container.
+	/// Insert a range of elements into the database. The range is
+	/// [first, last), which contains elements that can
+	/// be converted to type ddt automatically.
+	/// See the handle requirement in class details to pass correct
+	/// database/environment handles.
+	/// This function supports auto-commit.
+	/// \param dbp The database handle.
+	/// \param envp The database environment handle.
+	/// \param first The closed boundary of the range.
+	/// \param last The open boundary of the range.
+	/// \sa db_container(Db*, DbEnv*)
+	template <class InputIterator> 
+	db_map(Db *dbp, DbEnv* envp, InputIterator first, 
+	    InputIterator last) : db_container(dbp, envp)
+	{
+		const char *errmsg;
+
+		this->open_db_handles(dbp, envp, DB_BTREE, 
+		    DB_CREATE | DB_THREAD, 0);
+		if ((errmsg = verify_config(dbp, envp)) != NULL) {
+			THROW(InvalidArgumentException, ("Db*", errmsg));
+		}
+		this->set_db_handle_int(dbp, envp);
+
+		this->begin_txn();
+		try {
+			insert(first, last);
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+		this->commit_txn();
+	}
+
+	// Copy constructor. The object is initialized to have the same 
+	// contents as the x map object, do not copy properties because
+	// if we copy things like pdb, we are storing to the same db, so we
+	// create a new database, use it as the backing db, and store data 
+	// into it.
+	/// Copy constructor.
+	/// Create an database and insert all key/data pairs in x into this
+	/// container. x's data members are not copied.
+	/// This function supports auto-commit.
+	/// \param x The other container to initialize this container.
+	/// \sa db_container(const db_container&)
+	db_map(const db_map<kdt, ddt, value_type_sub, iterator>& x) : 
+	    db_container(x)
+	{
+		verify_db_handles(x);
+		this->set_db_handle_int(this->clone_db_config(
+		    x.get_db_handle()), x.get_db_env_handle());
+		assert(this->get_db_handle() != NULL);
+		
+		this->begin_txn();
+		try {
+			copy_db((db_map<kdt, ddt, value_type_sub, iterator>&)x);
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+		this->commit_txn();
+	}
+
+	virtual ~db_map(){}
+	//@}
+	////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////
+	// Begin insert function definitions.
+	/// Container content assignment operator.
+	/// This function supports auto-commit.
+	/// \param x The other container whose key/data pairs will be inserted
+	/// into this container. Old content in this containers are discarded.
+	/// \sa http://www.cplusplus.com/reference/stl/map/operator=/
+	inline const self& operator=(const self& x)
+	{
+		ASSIGNMENT_PREDCOND(x)
+		db_container::operator =(x);
+		verify_db_handles(x);
+		assert(this->get_db_handle() != NULL);
+		this->begin_txn();
+		try {
+			copy_db((self &)x);
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+		this->commit_txn();
+		return x;
+	}
+
+	/// \name Insert Functions
+	/// They have similiar usage as their C++ STL equivalents.
+	/// Note that when secondary index is enabled, each 
+	/// db_container can create a db_multimap secondary container, 
+	/// but the insert function is not functional for secondary containers.
+	/// \sa http://www.cplusplus.com/reference/stl/map/insert/
+	//@{
+	//
+	// Insert functions. Note that stl requires if the entry with x.key 
+	// already exists, insert should not overwrite that entry and the 
+	// insert should fail; but bdb Dbc::cursor(DB_KEYLAST) will replace
+	// existing data with new one, so we will first find whether we
+	// have this data, if have, return false;
+	//
+	// Can not internally use begin/commit_txn to wrap this call because 
+	// it returns an iterator, which is closed after commit_txn(), and
+	// reopening it is wrong in multithreaded access.
+	/// Insert a single key/data pair if the key is not in the container.
+	/// \param x The key/data pair to insert.
+	/// \return A pair P, if insert OK, i.e. the inserted key wasn't in the
+	/// container, P.first will be the iterator sitting on the inserted
+	/// key/data pair, and P.second is true; otherwise P.first is an 
+	/// invalid iterator and P.second is false.
+	pair<iterator,bool> insert (const value_type& x ) 
+	{
+		pair<iterator,bool> ib;
+		iterator witr;
+
+		init_itr(witr);
+		open_itr(witr);
+
+		if (witr.move_to(x.first) == 0) {// has it
+			ib.first = witr;
+			ib.second = false;
+			// Cursor movements are not logged, no need to 
+			// use transaction here.
+			return ib;
+		} 
+	
+		witr.itr_status_ = witr.pcsr_->insert(x.first, x.second, 
+		    DB_KEYLAST);
+		assert(witr.itr_status_ == 0);
+		witr.refresh(false);
+		ib.first = witr;
+		ib.second = true;
+
+		return ib;
+	}
+
+	/// Insert with hint position. We ignore the hint position because 
+	/// Berkeley DB knows better where to insert.
+	/// \param position The hint position.
+	/// \param x The key/data pair to insert.
+	/// \return The iterator sitting on the inserted key/data pair, or an
+	/// invalid iterator if the key was already in the container.
+	inline iterator insert (iterator position, const value_type& x ) 
+	{
+		pair<iterator,bool> ib = insert(x);
+		return ib.first;
+	}
+
+	// Member function template overload.
+	/// Range insertion. Insert a range [first, last) of key/data pairs
+	/// into this container.
+	/// \param first The closed boundary of the range.
+	/// \param last The open boundary of the range.
+	void insert (const db_map_base_iterator<kdt, realddt, ddt>& first, 
+	    const db_map_base_iterator<kdt, realddt, ddt>& last) 
+	{
+		db_map_base_iterator<kdt, realddt, ddt> ii;
+		iterator witr;
+
+		init_itr(witr);
+		open_itr(witr);
+
+		for (ii = first; ii != last; ++ii)
+			witr.pcsr_->insert(ii->first, ii->second, 
+			    DB_KEYLAST);	
+	}
+
+	/// Range insertion. Insert a range [first, last) of key/data pairs
+	/// into this container.
+	/// \param first The closed boundary of the range.
+	/// \param last The open boundary of the range.
+	template<typename InputIterator>
+	void insert (InputIterator first, InputIterator last) 
+	{
+		InputIterator ii;
+		iterator witr;
+
+		init_itr(witr);
+		open_itr(witr);
+
+		for (ii = first; ii != last; ++ii)
+			witr.pcsr_->insert(ii->first, ii->second, 
+			    DB_KEYLAST);	
+	}
+	//@}
+	////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////
+	// Begin functions that create iterators.
+	/// \name Iterator Functions
+	/// The parameters in begin functions of this group have identical
+	/// meaning to thoes in db_vector::begin, refer to those functions
+	/// for details.
+	/// \sa db_vector::begin()
+	//@{
+	/// Begin a read-write or readonly iterator which sits on the first
+	/// key/data pair of the database. 
+	/// \param rmw Same as that of 
+	/// db_vector::begin(ReadModifyWrite, bool, BulkRetrievalOption, bool);
+	/// \param bulkretrieval Same as that of 
+	/// db_vector::begin(ReadModifyWrite, bool, BulkRetrievalOption, bool);
+	/// \param directdb_get Same as that of
+	/// db_vector::begin(ReadModifyWrite, bool, BulkRetrievalOption, bool);
+	/// \param readonly Same as that of 
+	/// db_vector::begin(ReadModifyWrite, bool, BulkRetrievalOption, bool);
+	/// \return The created iterator.
+	/// \sa db_vector::begin(ReadModifyWriteOption, bool, 
+	/// BulkRetrievalOption, bool)
+	//
+	iterator begin(ReadModifyWriteOption rmw = 
+	    ReadModifyWriteOption::no_read_modify_write(),
+	    bool readonly = false, BulkRetrievalOption bulkretrieval = 
+	    BulkRetrievalOption::no_bulk_retrieval(), 
+	    bool directdb_get = true) 
+	{
+		bool b_rmw;
+		u_int32_t bulk_retrieval = 0;
+
+		b_rmw = (rmw == ReadModifyWriteOption::read_modify_write());
+		// Read only cursor don't need acquire write lock.
+		if (readonly && b_rmw)
+			b_rmw = false;
+		if (readonly && bulkretrieval == BulkRetrievalOption::
+		    BulkRetrieval)
+			bulk_retrieval = bulkretrieval.bulk_buf_size();
+
+		iterator itr(dynamic_cast<db_container*>(this), 
+		    bulk_retrieval, b_rmw, directdb_get, readonly);
+
+		open_itr(itr, readonly);
+		itr.first();
+		return itr;
+	}
+
+	/// Begin a read-only iterator.
+	/// \param bulkretrieval Same as that of 
+	/// begin(ReadModifyWrite, bool, BulkRetrievalOption, bool);
+	/// \param directdb_get Same as that of
+	/// begin(ReadModifyWrite, bool, BulkRetrievalOption, bool);
+	/// \return The created const iterator.
+	/// \sa db_vector::begin(ReadModifyWrite, bool, BulkRetrievalOption,
+	/// bool);
+	const_iterator begin(BulkRetrievalOption bulkretrieval = 
+	    BulkRetrievalOption::no_bulk_retrieval(), 
+	    bool directdb_get = true) const 
+	{
+		u_int32_t b_bulk_retrieval = (bulkretrieval == 
+		    BulkRetrievalOption::BulkRetrieval ? 
+		    bulkretrieval.bulk_buf_size() : 0);
+
+		const_iterator itr((db_container*)this,
+		     b_bulk_retrieval, false, directdb_get, true);
+
+		open_itr(itr, true);
+		itr.first();
+		return itr;
+	}
+
+	/// \brief Create an open boundary iterator.
+	/// \return Returns an invalid iterator denoting the position after 
+	/// the last valid element of the container.
+	/// \sa db_vector::end()
+	inline iterator end()
+	{
+		iterator itr;
+
+		// end() is at an invalid position. We don't know what key it 
+		// refers, so itr_status_ and inval_pos_type are the only 
+		// data members to identify an iterator's position.
+		//
+		itr.itr_status_ = INVALID_ITERATOR_POSITION;
+		itr.inval_pos_type_ = iterator::IPT_AFTER_LAST;
+		itr.owner_ = (db_container*)this;
+		return itr;
+	}
+
+	/// \brief Create an open boundary iterator.
+	/// \return Returns an invalid const iterator denoting the position 
+	/// after the last valid element of the container.
+	/// \sa db_vector::end() const
+	inline const_iterator end() const
+	{
+		const_iterator itr;
+
+		// end() is at an invalid position. We don't know what key it 
+		// refers, so itr_status_ and inval_pos_type are the only 
+		// data members to identify an iterator's position.
+		//
+		itr.itr_status_ = INVALID_ITERATOR_POSITION;
+		itr.inval_pos_type_ = iterator::IPT_AFTER_LAST;
+		itr.owner_ = (db_container*)this;
+		return itr;
+	}
+
+	/// Begin a read-write or readonly reverse iterator which sits on the 
+	/// first key/data pair of the database. 
+	/// \param rmw Same as that of 
+	/// db_vector::begin(ReadModifyWrite, bool, BulkRetrievalOption, bool);
+	/// \param bulkretrieval Same as that of 
+	/// db_vector::begin(ReadModifyWrite, bool, BulkRetrievalOption, bool);
+	/// \param directdb_get Same as that of
+	/// db_vector::begin(ReadModifyWrite, bool, BulkRetrievalOption, bool);
+	/// \param read_only Same as that of 
+	/// db_vector::begin(ReadModifyWrite, bool, BulkRetrievalOption, bool);
+	/// \return The created iterator.
+	/// \sa db_vector::begin(ReadModifyWriteOption, bool, 
+	/// BulkRetrievalOption, bool)
+	/// \sa db_vector::begin(ReadModifyWrite, bool, BulkRetrievalOption,
+	/// bool);
+	reverse_iterator rbegin(ReadModifyWriteOption rmw = 
+	    ReadModifyWriteOption::no_read_modify_write(),
+	    bool read_only = false, BulkRetrievalOption bulkretrieval = 
+	    BulkRetrievalOption::no_bulk_retrieval(), 
+	    bool directdb_get = true) 
+	{
+		u_int32_t bulk_retrieval = 0;
+
+		iterator itr = end();
+		itr.rmw_csr_ = (rmw == (
+		    ReadModifyWriteOption::read_modify_write())) && !read_only;
+		itr.directdb_get_ = directdb_get;
+		itr.read_only_ = read_only;
+		if (read_only && bulkretrieval == BulkRetrievalOption::
+		    BulkRetrieval)
+			bulk_retrieval = bulkretrieval.bulk_buf_size();
+		itr.bulk_retrieval_ = bulk_retrieval;
+		reverse_iterator ritr(itr);
+		
+		return ritr;
+	}
+
+	/// Begin a read-only reverse iterator.
+	/// \param bulkretrieval Same as that of 
+	/// begin(ReadModifyWrite, bool, BulkRetrievalOption, bool);
+	/// \param directdb_get Same as that of
+	/// begin(ReadModifyWrite, bool, BulkRetrievalOption, bool);
+	/// \return The created const iterator.
+	/// \sa db_vector::begin(ReadModifyWrite, bool, BulkRetrievalOption, 
+	/// bool);
+	const_reverse_iterator rbegin(BulkRetrievalOption bulkretrieval = 
+	    BulkRetrievalOption::no_bulk_retrieval(), 
+	    bool directdb_get = true) const
+	{
+		const_iterator itr = end();
+		itr.bulk_retrieval_ = (bulkretrieval == 
+		    BulkRetrievalOption::BulkRetrieval ? 
+		    bulkretrieval.bulk_buf_size() : 0);
+		itr.directdb_get_ = directdb_get;
+		itr.read_only_ = true;
+		const_reverse_iterator ritr(itr);
+		
+		return ritr;
+	}
+
+	/// \brief Create an open boundary iterator.
+	/// \return Returns an invalid iterator denoting the position 
+	/// before the first valid element of the container.
+	/// \sa db_vector::rend()
+	inline reverse_iterator rend()
+	{
+		reverse_iterator ritr;
+		ritr.inval_pos_type_ = iterator::IPT_BEFORE_FIRST;
+		return ritr;
+	}
+
+	/// \brief Create an open boundary iterator.
+	/// \return Returns an invalid const iterator denoting the position 
+	/// before the first valid element of the container. 
+	/// \sa db_vector::rend() const
+	inline const_reverse_iterator rend() const
+	{
+		const_reverse_iterator ritr;
+		ritr.inval_pos_type_ = iterator::IPT_BEFORE_FIRST;
+		return ritr;
+	}
+	//@} // iterator functions
+	////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////
+	//
+	// Begin functions that return container metadata.
+	/// \name Metadata Functions
+	/// These functions return metadata about the container.
+	//@{
+	/// Get container category.
+	/// Determines whether this container object is a std::map<> 
+	/// equivalent(when returns false) or that of hash_map<> 
+	/// class(when returns true). This method is not in stl, but it
+	/// may be called by users because some operations are not supported
+	/// by both type(map/hash_map) of containers, you need to call this
+	/// function to distinguish the two types. dbstl will not stop you
+	/// from calling the wrong methods of this class.
+	/// \return Returns true if this container is a hash container based
+	/// on a Berkeley DB hash database; returns false if it is based on a
+	/// Berkeley DB btree database.
+	//
+	inline bool is_hash() const
+	{
+		DBTYPE dbtype = DB_UNKNOWN;
+		int ret;
+
+		assert(this->get_db_handle() != NULL);
+		ret = this->get_db_handle()->get_type(&dbtype);
+		assert(ret == 0);
+		return dbtype == DB_HASH;
+	}
+
+	/// Only for std::hash_map, return number of hash bucket in use.
+	/// This function supports auto-commit.
+	/// \return The number of hash buckets of the database.
+	size_type bucket_count() const
+	{
+		DBTYPE dbtype;
+		u_int32_t flags;
+		void *sp;
+		size_type sz;
+		int ret;
+		DbTxn*txn;
+		
+		assert(this->get_db_handle() != NULL);
+		ret = this->get_db_handle()->get_type(&dbtype);
+		assert(ret == 0);
+		if (dbtype != DB_HASH) {
+			THROW(InvalidFunctionCall, ("db_map<>::bucket_count"));
+			
+		}
+		flags = DB_FAST_STAT;
+		
+		// Here we use current_txn(), so we will get a valid 
+		// transaction handle if we are using explicit transactions; 
+		// and NULL if we are using autocommit, in which case bdb 
+		// internal auto commit will be enabled automatically.
+		//
+		txn = ResourceManager::instance()->
+		    current_txn(this->get_db_handle()->get_env());
+		BDBOP(this->get_db_handle()->stat(txn, &sp, flags), ret);
+		
+		sz = (size_type)(((DB_HASH_STAT*)sp)->hash_buckets);
+		free(sp);
+		return sz;
+	}
+	
+	/// Get container size.
+	// Return size of the map, can control whether compute
+	// accurately(slower if db is huge) or not.
+	/// This function supports auto-commit.
+	/// \return Return the number of key/data pairs in the container.
+	/// \param accurate This function uses database's statistics to get
+	/// the number of key/data pairs. The statistics mechanism will either
+	/// scan the whole database to find the accurate number or use the
+	/// number of last accurate scanning, and thus much faster. If there 
+	/// are millions of key/data pairs, the scanning can take some while,
+	/// so in that case you may want to set the "accurate" parameter to 
+	/// false.
+	size_type size(bool accurate = true) const
+	{
+		u_int32_t flags;
+		void *sp;
+		DBTYPE dbtype;
+		size_t sz;
+		int ret;
+		DbTxn*txn;
+
+		flags = accurate ? 0 : DB_FAST_STAT;
+		BDBOP(this->get_db_handle()->get_type(&dbtype), ret);
+
+		// Here we use current_txn(), so we will get a valid 
+		// transaction handle if we are using explicit transactions; 
+		// and NULL if we are using autocommit, in which case bdb 
+		// internal auto commit will be enabled automatically.
+		//
+		txn = ResourceManager::instance()->
+		    current_txn(this->get_db_handle()->get_env());
+		BDBOP(this->get_db_handle()->stat(txn, &sp, flags), ret);
+
+		assert((dbtype == DB_BTREE) || (dbtype == DB_HASH));
+		// dbtype is BTREE OR HASH, no others.
+		sz = dbtype == DB_BTREE ? ((DB_BTREE_STAT*)sp)->
+		    bt_ndata : ((DB_HASH_STAT*)sp)->hash_ndata;
+		free(sp);
+		return sz;
+	}
+
+	/// Get max size.
+	/// The returned size is not the actual limit of database. See the
+	/// Berkeley DB limits to get real max size.
+	/// \return A meaningless huge number.
+	/// \sa db_vector::max_size()
+	inline size_type max_size() const
+	{
+		return SIZE_T_MAX;
+	}
+
+	/// Returns whether this container is empty.
+	/// This function supports auto-commit.
+	/// \return True if empty, false otherwise.
+	bool empty() const
+	{
+		// If we fail to move to the first record, the db is 
+		// supposed to be empty.
+		const_iterator witr;
+		bool ret;
+
+		try {
+			this->begin_txn();
+			init_itr(witr);
+			open_itr(witr, true);
+			ret = witr.first() != 0;
+			this->commit_txn();
+			return ret;
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+	}
+	//@}
+	////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////
+	// Begin element accessors.
+	//
+	// Don't use transaction wrapper(begin/commit_txn) here because 
+	// even insert(the only logged operation) is only part of the 
+	// whole expression---the use case is dmmap[key] = value; 
+	// So insert and another put call should
+	// be atomic, so there must be an outside transaction.
+	//
+	// As stated in STL specification, this method can't have "const" 
+	// modifier because it is likely to insert a new record.
+	/// Retrieve data element by key.
+	/// This function returns an reference to the underlying data element
+	/// of the specified key x. The returned object can be used to read or
+	/// write the data element of the key/data pair. 
+	/// Do use a data_type_wrap of db_map or value_type::second_type(they 
+	/// are the same) type of variable to hold the return value of this 
+	/// function.
+	/// \param x The target key to get value from.
+	/// \return Data element reference.
+	//
+	data_type_wrap operator[] (const key_type& x)
+	{
+		iterator witr, *pitr;
+		int ret;
+
+		init_itr(witr);
+		open_itr(witr, false);
+		
+		if (witr.move_to(x) != 0) {
+			ddt d;//default value
+			DbstlInitializeDefault<ddt> initdef(d);
+			// Insert (x, d) as place holder.
+			witr.pcsr_->insert(x, d, DB_KEYLAST);
+			// Should be OK this time.
+			ret = witr.move_to(x);
+			assert(ret == 0);
+			// Return the reference to the data item of x.
+		}
+		
+		//witr->curpair_.second._DB_STL_SetDelItr();
+		pitr = new iterator(witr);
+		data_type_wrap ref(pitr->curpair_.second);
+		ref._DB_STL_SetDelItr();
+		return ref;
+	}
+
+	// Only returns a right-value, no left value for assignment, so 
+	// directly return the value rather than the ElementRef/ElementHolder 
+	// wrapper. Must use a const reference to this container to call this
+	// const function.
+	//
+	/// Retrieve data element by key.
+	/// This function returns the value of the underlying data element of
+	/// specified key x. You can only read the element, but unable to 
+	/// update the element via the return value of this function. And you
+	/// need to use the container's const reference to call this method.
+	/// \param x The target key to get value from.
+	/// \return Data element, read only, can't be used to modify it.
+	const ddt operator[] (const key_type& x) const
+	{
+		iterator witr;
+
+		init_itr(witr);
+		open_itr(witr);
+		
+		// x is supposed to be in this map.
+		if (witr.move_to(x) != 0) {
+			THROW0(NoSuchKeyException);
+			
+		}
+		return witr.curpair_.second._DB_STL_value();
+	}
+	////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////
+	// Begin functions that erase elements from the container.
+	//
+	// Can not reopen external/outside iterator's cursor, pos must
+	// already be in a transactional context.
+	// There is identical function in db_multimap<> and db_multiset
+	// for this function, we MUST keep the code consistent on update!
+	// Go to db_multimap<>::erase(const key_type&) to see why.
+	/// \name Erase Functions
+	/// \sa http://www.cplusplus.com/reference/stl/map/erase/
+	//@{
+	/// Erase a key/data pair at specified position.
+	/// \param pos An valid iterator of this container to erase.
+	inline void erase (iterator pos) 
+	{
+		if (pos == end())
+			return;
+		pos.pcsr_->del();
+	}
+
+	/// Erase elements by key.
+	/// All key/data pairs with specified key x will be removed from 
+	/// underlying database.
+	/// This function supports auto-commit.
+	/// \param x The key to remove from the container.
+	/// \return The number of key/data pairs removed.
+	// There is identical function in db_multimap<> and db_multiset
+	// for this function, we MUST keep the code consistent on update!
+	// Go to db_multimap<>::erase(const key_type&) to see why.
+	//
+	size_type erase (const key_type& x) 
+	{
+		size_type cnt;
+		iterator itr;
+
+		this->begin_txn();
+		try {
+			pair<iterator, iterator> rg = equal_range(x);
+			for (itr = rg.first, cnt = 0; itr != rg.second; ++itr) {
+				cnt++;
+				itr.pcsr_->del();
+			}
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+		this->commit_txn();
+		return cnt;
+	}
+
+	// Can not be auto commit because first and last are already open.
+	// There is identical function in db_multimap<> and db_multiset
+	// for this function, we MUST keep the code consistent on update!
+	// Go to db_multimap<>::erase(const key_type&) to see why.
+	/// Range erase. Erase all key/data pairs within the valid range 
+	/// [first, last).
+	/// \param first The closed boundary of the range.
+	/// \param last The open boundary of the range.
+	inline void erase (iterator first, iterator last) 
+	{
+		iterator i;
+
+		for (i = first; i != last; ++i)
+			i.pcsr_->del();
+	}
+	//@}
+	
+	/// Swap content with container mp.
+	/// This function supports auto-commit.
+	/// \param mp The container to swap content with.
+	/// \param b_truncate: See db_vector::swap() for details.
+	/// \sa http://www.cplusplus.com/reference/stl/map/swap/ 
+	/// db_vector::clear()
+	void swap (db_map<kdt, ddt, value_type_sub>& mp, bool b_truncate = true)
+	{
+		Db *swapdb = NULL;
+		std::string dbfname(64, '\0');
+		
+		verify_db_handles(mp);
+		this->begin_txn();
+		try {
+			swapdb = this->clone_db_config(this->get_db_handle(), 
+			    dbfname);
+			db_map<kdt, ddt, value_type_sub> tmap(swapdb, 
+			    swapdb->get_env(), begin(), end());
+			clear(b_truncate);// Clear this db_map<> object.
+			typename db_map<kdt, ddt, value_type_sub>::
+			    iterator itr1, itr2;
+			itr1 = mp.begin();
+			itr2 = mp.end();
+			insert(itr1, itr2);
+			mp.clear(b_truncate);
+			itr1 = tmap.begin();
+			itr2 = tmap.end();
+			mp.insert(itr1, itr2);
+			tmap.clear();
+			
+			swapdb->close(0);
+			if (dbfname[0] != '\0') {
+				swapdb = new Db(NULL, DB_CXX_NO_EXCEPTIONS);
+				swapdb->remove(dbfname.c_str(), NULL, 0);
+				swapdb->close(0);
+				delete swapdb;
+			}
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}	
+		this->commit_txn();
+	}
+
+	/// Clear contents in this container.
+	/// This function supports auto-commit.
+	/// \param b_truncate See db_vector::clear(bool) for details.
+	/// \sa db_vector::clear(bool)
+	void clear (bool b_truncate = true) 
+	{
+		int ret;
+		u_int32_t flag;
+		DbEnv *penv = this->get_db_handle()->get_env();
+
+		if (b_truncate) {
+			ResourceManager::instance()->close_db_cursors(
+			    this->get_db_handle());
+			BDBOP2(this->get_db_handle()->truncate(
+			    ResourceManager::instance()->current_txn(penv), 
+			    NULL, 0), ret, this->abort_txn());
+		} else {
+			ReadModifyWriteOption brmw(
+			    ReadModifyWriteOption::no_read_modify_write());
+
+			BDBOP(penv->get_open_flags(&flag), ret);
+
+			// DB_RMW flag requires locking subsystem started.
+			if ((flag & DB_INIT_LOCK) || (flag & DB_INIT_CDB) || 
+			    (flag & DB_INIT_TXN))
+				brmw = 
+				    ReadModifyWriteOption::read_modify_write();
+			try {
+				// In if branch, truncate is capable of 
+				// autocommit internally.
+				this->begin_txn();
+				erase(begin(brmw, false), end());
+				this->commit_txn();
+			} catch (...) {
+				this->abort_txn();
+				throw;
+			}
+		}
+	}
+	////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////
+	// Begin functions that searches a key in the map.
+	/// \name Searching Functions
+	/// The following functions are returning iterators, and they by 
+	/// default return read-write iterators. If you intend to use the 
+	/// returned iterator only to read, you should call the const version
+	/// of each function using a const reference to this container.
+	/// Using const iterators can potentially promote concurrency a lot.
+	/// You can also set the readonly parameter to each non-const version
+	/// of the functions to true if you don't use the returned iterator
+	/// to write, which also promotes concurrency and overall performance.
+	//@{
+	/// Find the key/data pair with specified key x. 
+	/// \param x The target key to find.
+	/// \return The valid const iterator sitting on the key x, or an 
+	/// invalid one.
+	/// \sa http://www.cplusplus.com/reference/stl/map/find/
+	const_iterator find (const key_type& x) const
+	{
+		const_iterator witr;
+
+		init_itr(witr);
+		open_itr(witr, true);
+		if (witr.move_to(x)) 
+			return ((self *)this)->end();
+
+		return witr;
+	}
+
+	/// Find the greatest key less than or equal to x.
+	/// \param x The target key to find.
+	/// \return The valid const iterator sitting on the key, or an 
+	/// invalid one.
+	/// \sa http://www.cplusplus.com/reference/stl/map/lower_bound/
+	const_iterator lower_bound (const key_type& x) const 
+	{
+		const_iterator witr;
+
+		init_itr(witr);
+		open_itr(witr, true);
+		if (witr.move_to(x, DB_SET_RANGE)) 
+			return ((self *)this)->end();
+		
+		return witr;
+	}
+
+	/// Find the range within which all keys equal to specified key x.
+	/// \param x The target key to find.
+	/// \return The range [first, last).
+	/// \sa http://www.cplusplus.com/reference/stl/map/equal_range/
+	pair<const_iterator, const_iterator>
+	equal_range (const key_type& x) const 
+	{
+		pair<const_iterator,const_iterator> pr;
+		const_iterator witr;
+		kdt k;
+
+		init_itr(witr);
+		open_itr(witr, true);
+		if (witr.move_to(x, DB_SET_RANGE)) {
+			pr.first = ((self *)this)->end();
+			pr.second = ((self *)this)->end();
+		} else {
+			pr.first = witr;
+			// If no duplicate keys, move one next is sufficient.
+			if (witr.pcsr_->get_current_key(k) == 0 && k == x)
+				++witr;
+			pr.second = witr;
+		}
+		
+
+		return pr;
+	}
+
+	/// Find the key/data pair with specified key x. 
+	/// \param x The target key to find.
+	/// \param readonly Whether the returned iterator is readonly.
+	/// \return The valid iterator sitting on the key x, or an 
+	/// invalid one.
+	/// \sa http://www.cplusplus.com/reference/stl/map/find/
+	iterator find (const key_type& x, bool readonly = false) 
+	{
+		iterator witr;
+
+		init_itr(witr);
+		open_itr(witr, readonly);
+		if (witr.move_to(x)) 
+			return ((self *)this)->end();
+
+		return witr;
+	}
+
+	/// Find the greatest key less than or equal to x.
+	/// \param x The target key to find.
+	/// \param readonly Whether the returned iterator is readonly.
+	/// \return The valid iterator sitting on the key, or an 
+	/// invalid one.
+	/// \sa http://www.cplusplus.com/reference/stl/map/lower_bound/
+	iterator lower_bound (const key_type& x, bool readonly = false) 
+	{
+		iterator witr;
+
+		init_itr(witr);
+		open_itr(witr, readonly);
+		if (witr.move_to(x, DB_SET_RANGE)) 
+			return ((self *)this)->end();
+		
+		return witr;
+	}
+
+	/// Find the range within which all keys equal to specified key x.
+	/// \param x The target key to find.
+	/// \param readonly Whether the returned iterator is readonly.
+	/// \return The range [first, last).
+	/// \sa http://www.cplusplus.com/reference/stl/map/equal_range/
+	pair<iterator, iterator>
+	equal_range (const key_type& x, bool readonly = false) 
+	{
+		pair<iterator,iterator> pr;
+		iterator witr;
+		kdt k;
+
+		init_itr(witr);
+		open_itr(witr, readonly);
+		if (witr.move_to(x, DB_SET_RANGE)) {
+			pr.first = ((self *)this)->end();
+			pr.second = ((self *)this)->end();
+		} else {
+			pr.first = witr;
+			// If no dup, move one next is sufficient.
+			if (witr.pcsr_->get_current_key(k) == 0 && k == x)
+				++witr;
+			pr.second = witr;
+		}
+		
+
+		return pr;
+	}
+
+	/// Count the number of key/data pairs having specified key x.
+	/// \param x The key to count.
+	/// \return The number of key/data pairs having x as key within the
+	/// container.
+	/// \sa http://www.cplusplus.com/reference/stl/map/count/
+	size_type count (const key_type& x) const
+	{
+		int ret;
+		const_iterator witr;
+		try {
+			this->begin_txn();
+			init_itr(witr);
+			open_itr(witr, true);
+			ret = witr.move_to(x);
+			this->commit_txn();
+			if (ret != 0) 
+				return 0;// No such key/data pair.
+			// No duplicates, so it must be one, we don't call
+			// Dbc::count because we don't have to.
+			//
+			else
+				return 1;
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+		
+	}
+
+	/// Find the least key greater than x.
+	/// \param x The target key to find.
+	/// \return The valid iterator sitting on the key, or an 
+	/// invalid one.
+	/// \sa http://www.cplusplus.com/reference/stl/map/upper_bound/
+	const_iterator upper_bound (const key_type& x) const
+	{
+		const_iterator witr;
+
+		init_itr(witr);
+		open_itr(witr, true);
+
+		if (witr.move_to(x, DB_SET_RANGE)) 
+			return ((self *)this)->end();
+
+		kdt k;
+
+		// x exists in db, and witr.pcsr_ points to x in db.
+		if (witr.pcsr_->get_current_key(k) == 0 && k == x)
+			++witr;// No dup, so move one next is sufficient.
+
+		return witr;
+	}
+
+	/// Find the least key greater than x.
+	/// \param x The target key to find.
+	/// \param readonly Whether the returned iterator is readonly.
+	/// \return The valid iterator sitting on the key, or an 
+	/// invalid one.
+	/// \sa http://www.cplusplus.com/reference/stl/map/upper_bound/
+	iterator upper_bound (const key_type& x, bool readonly = false)
+	{
+		iterator witr;
+
+		init_itr(witr);
+		open_itr(witr, readonly);
+
+		if (witr.move_to(x, DB_SET_RANGE)) 
+			return ((self *)this)->end();
+
+		kdt k;
+
+		// x exists in db, and witr.pcsr_ points to x in db.
+		if (witr.pcsr_->get_current_key(k) == 0 && k == x)
+			++witr;// No dup, so move one next is sufficient.
+
+		return witr;
+	}
+	//@}
+	////////////////////////////////////////////////////////////////
+
+	// Compare function, return true if contents in m1 and m2 are 
+	// identical otherwise return false. 
+	// Note that we don't require the key-data pairs' order be identical
+	// Put into db_map<> rather than global to utilize transactional
+	// support.
+	/// Map content equality comparison operator.
+	/// This function does not rely on key order. For a set of keys S1 in
+	/// this container and another set of keys S2 of container m2, if 
+	/// set S1 contains S2 and S2 contains S1 (S1 equals to S2) and each
+	/// data element of a key K in S1 from this container equals the data
+	/// element of K in m2, the two db_map<> containers equal. Otherwise
+	/// they are not equal.
+	/// \param m2 The other container to compare against.
+	/// \return Returns true if they have equal content, false otherwise.
+	bool operator==(const db_map<kdt, ddt, value_type_sub>& m2) const
+	{
+		bool ret;
+		const db_map<kdt, ddt, value_type_sub>& m1 = *this;
+		COMPARE_CHECK(m2)
+		verify_db_handles(m2);
+		try {
+			this->begin_txn();
+			if (m1.size() != m2.size())
+				ret = false;
+			else {
+				typename db_map<kdt, ddt, value_type_sub>::
+				    const_iterator i1, i2;
+				
+				for (i1 = m1.begin(); i1 != m1.end(); ++i1) {
+					if (m2.count(i1->first) == 0) {
+						ret = false;
+						goto exit;
+					}
+					i2 = m2.find(i1->first);
+					if ((i2->second == i1->second) == 
+					    false) {
+						ret = false;
+						goto exit;
+					}
+				} // for
+
+				ret = true;
+			}
+exit:
+			this->commit_txn();
+			return ret;
+
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+	// Now that m1 and m2 has the same number of unique elements and all
+	// elements of m1 are in m2, thus there can be no element of m2 
+	// that dose not belong to m1, so we won't verify each element of 
+	// m2 are in m1.
+	//
+	}
+
+	/// Container unequality comparison operator.
+	/// \param m2 The container to compare against.
+	/// \return Returns false if equal, true otherwise.
+	bool operator!=(const db_map<kdt, ddt, value_type_sub>& m2) const
+	{
+		return !this->operator ==(m2);
+	}
+
+	
+protected:
+	
+	virtual const char* verify_config(Db*dbp, DbEnv* envp) const
+	{
+		DBTYPE dbtype;
+		u_int32_t oflags, sflags;
+		int ret;
+		const char *err = NULL;
+		
+		err = db_container::verify_config(dbp, envp);
+		if (err)
+			return err;
+
+		BDBOP(dbp->get_type(&dbtype), ret);
+		BDBOP(dbp->get_open_flags(&oflags), ret);
+		BDBOP(dbp->get_flags(&sflags), ret);
+
+		if (dbtype != DB_BTREE && dbtype != DB_HASH)
+			err = 
+"wrong database type, only DB_BTREE and DB_HASH allowed for db_map<> class";
+
+		if (oflags & DB_TRUNCATE)
+			err = 
+"do not specify DB_TRUNCATE flag to create a db_map<> object";
+		if ((sflags & DB_DUP) || (sflags & DB_DUPSORT))
+			err = 
+"db_map<> can not be backed by database permitting duplicate keys";
+		if (sflags & DB_RECNUM)
+			err = "no DB_RECNUM flag allowed in db_map<>";
+		
+		
+		return err;
+
+	}
+
+
+	typedef ddt mapped_type;
+	typedef int (*db_compare_fcn_t)(Db *db, const Dbt *dbt1, 
+	    const Dbt *dbt2);
+	typedef u_int32_t (*h_hash_fcn_t)
+	(Db *, const void *bytes, u_int32_t length);
+	typedef db_set_iterator<kdt> db_multiset_iterator_t;
+
+	static bool compare_keys(Db *pdb, const kdt& k1, const kdt& k2) 
+	{
+		DBTYPE dbtype;
+		int ret;
+		bool bret;
+		u_int32_t sz1, sz2;
+
+		assert(pdb != NULL);
+		ret = pdb->get_type(&dbtype);
+		assert(ret == 0);
+		db_compare_fcn_t comp = NULL;
+
+		if (dbtype == DB_BTREE)
+			BDBOP(pdb->get_bt_compare(&comp), ret);
+		else // hash
+			BDBOP(pdb->get_h_compare(&comp), ret);
+
+		DataItem key1(k1, true), key2(k2, true);
+		Dbt &kdbt1 = key1.get_dbt();
+		Dbt &kdbt2 = key2.get_dbt();
+		sz1 = kdbt1.get_size();
+		sz2 = kdbt2.get_size();
+		
+		if (comp == NULL) {
+			ret = memcmp(&k1, &k2, sz1 > sz2 ? sz2 : sz1);
+			return (ret == 0) ? (sz1 < sz2) : (ret < 0);
+		}
+		// Return strict weak ordering.
+		bret = (comp(pdb, &kdbt1, &kdbt2) < 0);
+		return bret;
+	}
+	
+	void open_itr(db_map_base_iterator<kdt, realddt, ddt>&itr, 
+	    bool readonly = false) const
+	{	
+		u_int32_t oflags = 0;
+		int ret;
+		DbEnv *penv = this->get_db_handle()->get_env();
+
+		if (!readonly && penv != NULL) {
+			BDBOP((penv->get_open_flags(&oflags)) , ret);
+			 if ((oflags & DB_INIT_CDB) != 0)
+				((self *)this)->set_cursor_open_flags(
+				    this->get_cursor_open_flags() | 
+				    DB_WRITECURSOR);
+		}
+
+		itr.itr_status_ = itr.pcsr_->open((db_container*)this, 
+		    this->get_cursor_open_flags());
+		itr.owner_ = (db_container*)this;
+	}
+
+	void open_itr(const_reverse_iterator
+	    &itr, bool readonly = false) const
+	{	
+		u_int32_t oflags = 0;
+		int ret;
+		DbEnv *penv = this->get_db_handle()->get_env();
+
+		if (!readonly && penv != NULL) {
+			BDBOP((penv->get_open_flags(&oflags)) , ret);
+			 if ((oflags & DB_INIT_CDB) != 0)
+				((self *)this)->set_cursor_open_flags(
+				    this->get_cursor_open_flags() | 
+				    DB_WRITECURSOR);
+		}
+		itr.itr_status_ = itr.pcsr_->open((db_container*)this, 
+		    this->get_cursor_open_flags());
+		itr.owner_ = (db_container*)this;
+	}
+
+	inline void init_itr(db_map_base_iterator<kdt, realddt, ddt> &
+	    witr) const {
+		typedef DbCursor<kdt, ddt> cursor_type;
+		witr.pcsr_.set_cursor(new cursor_type());
+		witr.owner_ = (db_container*)this;
+	}
+
+	// Do not use begin_txn/commit_txn in non-public(internal) methods, 
+	// only wrap in public methods.
+	//
+	inline void copy_db(db_map<kdt, ddt, value_type_sub, iterator> &x)
+	{	 
+
+		// Make sure clear can succeed if there are cursors 
+		// open in other threads.
+		clear(false);
+		insert(x.begin(), x.end());
+		
+	}
+
+};//db_map
+//@}
+
+
+//////////////////////////////////////////////////////////////////////////
+//////////////////////////////////////////////////////////////////////////
+//
+// db_multimap class template definition
+//
+// This class derives from db_map<>, using many of its methods,
+// it also hides some functions that should not be used in
+// this class, such as operator[].
+//
+// The underlying db must allow duplicate.
+// iterator_t is default argument, see forward declaration at the
+// head of this file.
+// iterator_t is default argument, see forward declaration at the
+// head of this file
+//
+/// \ingroup dbstl_containers
+//@{
+/// This class is the combination of std::multimap and hash_multimap. By 
+/// setting database handles as DB_BTREE or DB_HASH type respectively, you
+/// will be using an equivalent of std::multimap or hash_multimap respectively.
+/// Database(dbp) and environment(penv) handle requirement:
+/// The dbp handle must meet the following requirement:
+/// 1. Database type should be DB_BTREE or DB_HASH.
+/// 2. Either DB_DUP or DB_DUPSORT flag must be set. Note that so far 
+/// Berkeley DB does not allow DB_DUPSORT be set and the database is storing
+/// identical key/data pairs, i.e. we can't store two (1, 2), (1, 2) pairs 
+/// into a database D with DB_DUPSORT flag set, but only can do so with DB_DUP
+/// flag set; But we can store a (1, 2) pair and a (1, 3) pair into D with
+/// DB_DUPSORT flag set. So if your data set allows DB_DUPSORT flag, you
+/// should set it to gain a lot of performance promotion.
+/// 3. No DB_RECNUM flag set.
+/// 4. No DB_TRUNCATE specified in database open flags.
+/// 5. DB_THREAD must be set if you are sharing the database handle across 
+/// multiple threads directly, or indirectly by sharing the container object
+/// across multiple threads.
+/// \param kdt The key data type.
+/// \param ddt The data data type. db_multimap stores key/data pairs.
+/// \param value_type_sub Do not specify anything if ddt type is a 
+/// class/struct type; Otherwise, specify ElementHolder<ddt> to it.
+/// \param iterator_t Never specify anything to this type parameter. It is
+/// only used internally.
+/// \sa db_container db_map
+template<Typename kdt, Typename ddt, Typename value_type_sub, 
+    Typename iterator_t>
+class _exported db_multimap : public db_map<kdt, ddt, 
+    value_type_sub, iterator_t> 
+{
+protected:
+	typedef db_multimap<kdt, ddt, value_type_sub, iterator_t> self;
+	typedef db_map<kdt, ddt, value_type_sub, iterator_t> base;
+public:
+	typedef iterator_t iterator;
+	typedef typename iterator::const_version const_iterator;
+	typedef db_reverse_iterator<iterator, const_iterator> reverse_iterator;
+	typedef db_reverse_iterator<const_iterator, iterator> 
+	    const_reverse_iterator;
+	typedef kdt key_type;
+	typedef ddt data_type;
+	typedef value_type_sub data_type_wrap;
+	typedef pair<kdt, value_type_sub> value_type_wrap;
+	typedef pair<kdt, ddt> value_type;
+	typedef value_type_wrap* pointer;
+	typedef value_type_wrap& reference; 
+	typedef const value_type& const_reference; 
+	typedef size_t size_type;
+	typedef ptrdiff_t difference_type;
+
+	////////////////////////////////////////////////////////////////
+	// Begin constructors and destructor
+	/// Constructor.
+	/// See class detail for handle requirement.
+	/// \param dbp The database handle.
+	/// \param envp The database environment handle.
+	/// \sa db_map::db_map(Db*, DbEnv*) db_vector::db_vector(Db*, DbEnv*)
+	explicit db_multimap (Db *dbp = NULL, DbEnv* envp = NULL) : 
+	    base(*(new BulkRetrievalOption(
+	    BulkRetrievalOption::BulkRetrieval)))
+	{
+		const char *errmsg;
+
+		this->init_members(dbp, envp);
+		this->open_db_handles(dbp, envp, DB_BTREE, DB_CREATE | 
+		    DB_THREAD, DB_DUP);
+		// We can't call base(dbp, envp) here because it will verify 
+		// failed and we can't call db_container directly, it is 
+		// illegal to do so.
+		if ((errmsg = verify_config(dbp, envp)) != NULL) {
+			THROW(InvalidArgumentException, ("Db*", errmsg));
+			
+		}
+		this->set_db_handle_int(dbp, envp);
+		this->set_auto_commit(dbp);
+	}
+
+	/// Iteration constructor.
+	/// Iterates between first and last, setting
+	/// a copy of each of the sequence of elements as the content of 
+	/// the container object. 
+	/// This function supports auto-commit.
+	/// See class detail for handle requirement.
+	/// \param dbp The database handle.
+	/// \param envp The database environment handle.
+	/// \param first The closed boundary of the range.
+	/// \param last The open boundary of the range.
+	/// \sa db_map::db_map(Db*, DbEnv*, InputIterator, InputIterator)
+	/// db_vector::db_vector(Db*, DbEnv*)
+	//
+	template <class InputIterator> 
+	db_multimap (Db *dbp, DbEnv* envp, InputIterator first, 
+	    InputIterator last) : base(*(new BulkRetrievalOption(
+	    BulkRetrievalOption::BulkRetrieval)))
+	{
+		const char *errmsg;
+
+		this->init_members(dbp, envp);
+		this->open_db_handles(dbp, envp, DB_BTREE, DB_CREATE | 
+		    DB_THREAD, DB_DUP);
+		// Note that we can't call base(dbp, envp) here because it 
+		// will verify failed; And we can't call db_container 
+		// directly because it is illegal to do so.
+		if ((errmsg = verify_config(dbp, envp)) != NULL) {
+			THROW(InvalidArgumentException, ("Db*", errmsg));
+			
+		}
+		this->set_db_handle_int(dbp, envp);
+		this->set_auto_commit(dbp);
+
+
+		this->begin_txn();
+		try {
+			insert(first, last);
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+		this->commit_txn();
+	}
+
+	/// Copy constructor.
+	/// Create an database and insert all key/data pairs in x into this
+	/// container. x's data members are not copied.
+	/// This function supports auto-commit.
+	/// \param x The other container to initialize this container.
+	/// \sa db_container(const db_container&) db_map(const db_map&)
+	db_multimap (const self& x) : base(*(new BulkRetrievalOption(
+	    BulkRetrievalOption::BulkRetrieval)))
+	{
+		this->init_members(x);
+		verify_db_handles(x);
+		this->set_db_handle_int(this->clone_db_config(
+		    x.get_db_handle()), x.get_db_env_handle());
+		assert(this->get_db_handle() != NULL);
+		
+		this->begin_txn();
+		try {
+			copy_db((self&)x);
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+		this->commit_txn();
+	}
+
+	virtual ~db_multimap(){}
+	////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////
+	// Begin functions that modify multimap content, e.g. insert, 
+	// erase, assignment and swap.
+	//
+	/// Container content assignment operator.
+	/// This function supports auto-commit.
+	/// \param x The other container whose key/data pairs will be inserted
+	/// into this container. Old content in this containers are discarded.
+	/// \sa http://www.cplusplus.com/reference/stl/multimap/operator=/
+	inline const self& operator=(const self&x)
+	{
+		ASSIGNMENT_PREDCOND(x)
+		db_container::operator =(x);
+		verify_db_handles(x);
+		assert(this->get_db_handle() != NULL);
+		this->begin_txn();
+		try {
+			this->copy_db((self &)x);
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+		this->commit_txn();
+		return x;
+		
+	}
+
+	/// \name Insert Functions
+	/// \sa http://www.cplusplus.com/reference/stl/multimap/insert/
+	//@{
+	/// Range insertion. Insert a range [first, last) of key/data pairs
+	/// into this container.
+	/// \param first The closed boundary of the range.
+	/// \param last The open boundary of the range.
+	template<typename InputIterator>
+	void insert (InputIterator first, InputIterator last) 
+	{
+		InputIterator ii;
+		iterator witr;
+
+		init_itr(witr);
+		open_itr(witr);
+
+		for (ii = first; ii != last; ++ii)
+			witr.pcsr_->insert(ii->first, ii->second, 
+			    DB_KEYLAST);	
+	}
+
+	// Compiler can't see the inherited version, unknown why.
+	/// Range insertion. Insert a range [first, last) of key/data pairs
+	/// into this container.
+	/// \param first The closed boundary of the range.
+	/// \param last The open boundary of the range.
+	inline void insert (const_iterator& first, const_iterator& last) {
+		base::insert(first, last);
+	}
+
+	// Insert x into this container, the other two versions are 
+	// inherited from db_map<> class.
+	// Methods returning an iterator or using an iterator as parameter 
+	// can not be internally wrapped by 
+	// begin/commit_txn because a cursor is inside its transaction, it 
+	// must have been closed after transaction commit, and reopen is 
+	// unsafe in multithreaded access.
+	//
+	/// Insert a single key/data pair if the key is not in the container.
+	/// \param x The key/data pair to insert.
+	/// \return A pair P, if insert OK, i.e. the inserted key wasn't in the
+	/// container, P.first will be the iterator sitting on the inserted
+	/// key/data pair, and P.second is true; otherwise P.first is an 
+	/// invalid iterator and P.second is false.
+	inline iterator insert (const value_type& x) 
+	{
+		iterator witr;
+
+		this->init_itr(witr);
+		this->open_itr(witr);
+		witr.itr_status_ = witr.pcsr_->insert(x.first, x.second, 
+		    DB_KEYLAST);
+		witr.refresh(false);
+		return witr;
+	}
+	//@}
+
+	/// Swap content with another multimap container.
+	/// This function supports auto-commit.
+	/// \param mp The other container to swap content with.
+	/// \param b_truncate See db_map::swap() for details.
+	/// \sa db_vector::clear()
+	void swap (db_multimap<kdt, ddt, value_type_sub>& mp, 
+	    bool b_truncate = true)
+	{
+		Db *swapdb = NULL;
+		std::string dbfname(64, '\0');
+
+		verify_db_handles(mp);
+		this->begin_txn();
+		try {
+			swapdb = this->clone_db_config(this->get_db_handle(), 
+			    dbfname);
+			
+			db_multimap<kdt, ddt, value_type_sub> tmap(
+			    swapdb, swapdb->get_env(),
+			    this->begin(), this->end());
+			// Clear this db_multimap<> object.
+			this->clear(b_truncate);
+			typename db_multimap<kdt, ddt, value_type_sub>::
+			    iterator mpbitr, mpeitr;
+
+			mpbitr = mp.begin();
+			mpeitr = mp.end();
+			insert(mpbitr, mpeitr);
+			mp.clear(b_truncate);
+			mpbitr = tmap.begin();
+			mpeitr = tmap.end();
+			mp.insert(mpbitr, mpeitr);
+			tmap.clear();
+			
+			swapdb->close(0);
+			if (dbfname[0] != '\0') {
+				swapdb = new Db(NULL, DB_CXX_NO_EXCEPTIONS);
+				swapdb->remove(dbfname.c_str(), NULL, 0);
+				swapdb->close(0);
+				delete swapdb;
+			}
+			this->commit_txn();
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+		
+	}
+
+	// This method has identical code to db_map<>::erase(const key_type&), 
+	// but we can NOT simply inherit and use 
+	// that version because:
+	// 1. The db_map<>::erase called equal_range which is overloaded in 
+	//	db_multimap, so if we want the inherited erase to call the right
+	//	version of equal_range, we have to make equal_range virtual
+	// 2.  Making equal_range virtual will make the code not build--- The 
+	//	default template parameter can't be replaced by real parameter, 
+	//	unknow why.
+	// So we have to copy the code from db_map<> to here, and keep the 
+	// code consistent on each update.
+	// Also, when I copy only this function, I found other erase overloaded 
+	// functions also have to be copied from db_map<> to db_multimap and 
+	// db_multiset, otherwise the code don't build, so I 
+	// finally have to copy all versions of erase functions into db_multiset
+	// and db_multimap. When updating an erase function, do update all 
+	// three versions.
+	/// \name Erase Functions
+	/// \sa http://www.cplusplus.com/reference/stl/multimap/erase/
+	//@{
+	/// Erase elements by key.
+	/// All key/data pairs with specified key x will be removed from 
+	/// underlying database.
+	/// This function supports auto-commit.
+	/// \param x The key to remove from the container.
+	/// \return The number of key/data pairs removed.
+	size_type erase (const key_type& x) 
+	{
+		size_type cnt;
+		iterator itr;
+
+		this->begin_txn();
+		try {
+			pair<iterator, iterator> rg = equal_range(x);
+			for (itr = rg.first, cnt = 0; itr != rg.second; ++itr) {
+				cnt++;
+				itr.pcsr_->del();
+			}
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+		this->commit_txn();
+		return cnt;
+	}
+
+	// Can not reopen external/outside iterator's cursor, pos must
+	// already be in a transactional context.
+	// There is identical function in db_multimap<> and db_multiset
+	// for this function, we MUST keep the code consistent on update!
+	// Go to db_multimap<>::erase(const key_type&) to see why.
+	//
+	/// Erase a key/data pair at specified position.
+	/// \param pos An valid iterator of this container to erase.
+	inline void erase (iterator pos) 
+	{
+		if (pos == this->end())
+			return;
+		pos.pcsr_->del();
+	}
+
+	// Can not be auto commit because first and last are already open.
+	// There is identical function in db_multimap<> and db_multiset
+	// for this function, we MUST keep the code consistent on update!
+	// Go to db_multimap<>::erase(const key_type&) to see why.
+	//
+	/// Range erase. Erase all key/data pairs within the valid range 
+	/// [first, last).
+	/// \param first The closed boundary of the range.
+	/// \param last The open boundary of the range.
+	inline void erase (iterator first, iterator last) 
+	{
+
+		for (iterator i = first; i != last; ++i)
+			i.pcsr_->del();
+	}
+	//@}
+	////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////
+	// Begin functions that searches a key in the multimap.
+	/// \name Searching Functions
+	/// See of db_map's searching functions group for details about 
+	/// iterator, function version and parameters.
+	/// \sa db_map
+	//@{
+	/// Find the range within which all keys equal to specified key x.
+	/// \param x The target key to find.
+	/// \return The range [first, last).
+	/// \sa http://www.cplusplus.com/reference/stl/multimap/equal_range/
+	pair<const_iterator, const_iterator>
+	equal_range (const key_type& x) const
+	{
+		pair<const_iterator,const_iterator> pr;
+		const_iterator witr;
+		kdt k;
+
+		this->init_itr(witr);
+		this->open_itr(witr, true);
+		// Move witr to x if this contains x and return the itr, or if 
+		// no x, position witr to the least key greater than x.
+		//
+		if (witr.move_to(x, DB_SET_RANGE)) {
+			pr.first =  ((self *)this)->end();
+			pr.second = ((self *)this)->end();
+		} else {
+			pr.first = witr;
+			
+			// No dup, so move one next is sufficient.
+			if (witr.pcsr_->get_current_key(k) == 0 && k == x)
+				witr.next(DB_NEXT_NODUP);
+			pr.second = witr;
+		}
+			
+		return pr;
+	}
+
+	/// Find the range within which all keys equal to specified key x.
+	/// \param x The target key to find.
+	/// \param readonly Whether the returned iterator is readonly.
+	/// \return The range [first, last).
+	/// \sa http://www.cplusplus.com/reference/stl/multimap/equal_range/
+	pair<iterator,iterator>
+	equal_range (const key_type& x, bool readonly = false) 
+	{
+		pair<iterator,iterator> pr;
+		iterator witr;
+		kdt k;
+
+		this->init_itr(witr);
+		this->open_itr(witr, readonly);
+		// Move witr to x if this contains x and return the itr, or if 
+		// no x, position witr to the least key greater than x.
+		//
+		if (witr.move_to(x, DB_SET_RANGE)) {
+			pr.first =  ((self *)this)->end();
+			pr.second = ((self *)this)->end();
+		} else {
+			pr.first = witr;
+			
+			// No dup, so move one next is sufficient.
+			if (witr.pcsr_->get_current_key(k) == 0 && k == x)
+				witr.next(DB_NEXT_NODUP);
+			pr.second = witr;
+		}
+			
+		return pr;
+	}
+
+	/// Find equal range and number of key/data pairs in the range.
+	/// This function also returns the number of elements within the 
+	/// returned range via the out parameter nelem.
+	/// \param x The target key to find.
+	/// \param nelem The output parameter to take back the number of 
+	/// key/data pair in the returned range.
+	/// \sa http://www.cplusplus.com/reference/stl/multimap/equal_range/
+	pair<const_iterator, const_iterator>
+	equal_range_N (const key_type& x, size_t& nelem) const
+	{
+		int ret;
+		pair<const_iterator,const_iterator> pr;
+		size_t stepped;
+		const_iterator witr;
+		kdt k;
+
+		this->init_itr(witr);
+		this->open_itr(witr, true);
+		// Move witr to x if this contains x and return the itr, or if 
+		// no x, position witr to the least key greater than x.
+		//
+		if (witr.move_to(x, DB_SET_RANGE)) {
+			pr.first = ((self *)this)->end();
+			pr.second = ((self *)this)->end();
+			nelem = 0;
+		} else {
+			pr.first = witr;
+			if (witr.pcsr_->get_current_key(k) == 0 && k == x) {
+				for (stepped = 1, ret = 
+				    witr.pcsr_->next(DB_NEXT_DUP); ret == 0;
+				    ret = witr.pcsr_->next(DB_NEXT_DUP),
+				    stepped += 1)
+					;
+				pr.second = ++witr;
+				nelem = stepped;
+			} else {
+				pr.second = witr;
+				nelem = 0;
+			}
+		}
+		return pr;
+	}
+
+	/// Find equal range and number of key/data pairs in the range.
+	/// This function also returns the number of elements within the 
+	/// returned range via the out parameter nelem.
+	/// \param x The target key to find.
+	/// \param nelem The output parameter to take back the number of 
+	/// key/data pair in the returned range.
+	/// \param readonly Whether the returned iterator is readonly.
+	/// \sa http://www.cplusplus.com/reference/stl/multimap/equal_range/
+	//
+	pair<iterator,iterator>
+	equal_range_N (const key_type& x, size_t& nelem, 
+	    bool readonly = false)
+	{
+		int ret;
+		pair<iterator,iterator> pr;
+		size_t stepped;
+		iterator witr;
+		kdt k;
+
+		this->init_itr(witr);
+		this->open_itr(witr, readonly);
+		// Move witr to x if this contains x and return the itr, or if 
+		// no x, position witr to the least key greater than x.
+		//
+		if (witr.move_to(x, DB_SET_RANGE)) {
+			pr.first = ((self *)this)->end();
+			pr.second = ((self *)this)->end();
+			nelem = 0;
+		} else {
+			pr.first = witr;
+			if (witr.pcsr_->get_current_key(k) == 0 && k == x) {
+				for (stepped = 1, ret = 
+				    witr.pcsr_->next(DB_NEXT_DUP); ret == 0;
+				    ret = witr.pcsr_->next(DB_NEXT_DUP),
+				    stepped += 1)
+					;
+				pr.second = ++witr;
+				nelem = stepped;
+			} else {
+				pr.second = witr;
+				nelem = 0;
+			}
+		}
+		return pr;
+	}
+
+	/// Count the number of key/data pairs having specified key x.
+	/// \param x The key to count.
+	/// \return The number of key/data pairs having x as key within the
+	/// container.
+	/// \sa http://www.cplusplus.com/reference/stl/multimap/count/
+	size_type count (const key_type& x) const
+	{
+		int ret;
+		size_type cnt;
+		iterator witr;
+
+		try {
+			this->begin_txn();
+			this->init_itr(witr);
+			this->open_itr(witr, true);
+			ret = witr.move_to(x);
+			if (ret) 
+				cnt = 0;
+			else
+				cnt = witr.pcsr_->count();
+			this->commit_txn();
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+
+		return cnt;
+	}
+
+	/// Find the least key greater than x.
+	/// \param x The target key to find.
+	/// \return The valid iterator sitting on the key, or an 
+	/// invalid one.
+	/// \sa http://www.cplusplus.com/reference/stl/multimap/upper_bound/
+	const_iterator upper_bound (
+	    const key_type& x) const
+	{
+		int ret;
+		const_iterator witr;
+
+		this->init_itr(witr);
+		this->open_itr(witr, true);
+
+		// No key equal to or greater than x.
+		if (witr.move_to(x, DB_SET_RANGE)) 
+			return ((self *)this)->end();
+
+		kdt k;
+		// x exists in db, and witr.pcsr_ points to x in db, 
+		// need to move cursor to next different key.
+		//
+		if (witr.pcsr_->get_current_key(k) == 0 && k == x) 
+			ret = witr.next(DB_NEXT_NODUP); 
+
+		return witr;
+	}
+
+	/// Find the least key greater than x.
+	/// \param x The target key to find.
+	/// \param readonly Whether the returned iterator is readonly.
+	/// \return The valid iterator sitting on the key, or an 
+	/// invalid one.
+	/// \sa http://www.cplusplus.com/reference/stl/multimap/upper_bound/
+	iterator upper_bound (const key_type& x, bool readonly = false) 
+	{
+		int ret;
+		iterator witr;
+
+		this->init_itr(witr);
+		this->open_itr(witr, readonly);
+
+		// No key equal to or greater than x.
+		if (witr.move_to(x, DB_SET_RANGE)) 
+			return ((self *)this)->end();
+
+		kdt k;
+		// x exists in db, and witr.pcsr_ points to x in db, 
+		// need to move cursor to next different key.
+		//
+		if (witr.pcsr_->get_current_key(k) == 0 && k == x) 
+			ret = witr.next(DB_NEXT_NODUP); 
+
+		return witr;
+	}
+	//@}
+	////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////
+	// Begin functions that compare container content.
+	//
+	// In hash_multimap this function is a global compare function, 
+	// return true if contents in m1 and m2 are identical
+	// otherwise return false. But we have multiple reasons to make
+	// it a member of db_multimap<>:
+	// 1. There need to be a temporary set to store values of a range, and
+	//   db_multimap<>  is quite likely to store huge amount of data, 
+	//   not suitable to store into std::set, let alone std::set is not 
+	//   completely multithread-safe, thus we store them into db_set<>, 
+	//   thus we need a temporary db handle, and call 
+	//   db_container::clone_db_handle() function to open the db handle.
+	// 2. We need the transactional support. Making this function 
+	//   autocommit is good to eliminate phantom issues.
+	// Note that we don't require the key-data pairs' order be identical,
+	// but we assume identical records of keys are adjacent, so that 
+	// iteration will go through them all one by one; Also, the records'
+	// order of identical keys are unpridictable and irrelivent, so we 
+	// should treat values of a equal range a set, and compare two value 
+	// sets for equality when comparing a equal range of key X.
+	//
+	/**
+	Returns whether the two containers have identical content.
+	This function does not rely on key order. For a set of keys S1 in this
+	container and another set of keys S2 of container m2, if set S1 
+	contains S2 and S2 contains S1 (S1 equals to S2) and each set of data
+	elements of any key K in S1 from this container equals the set of data
+	elements of K in m2, the two db_multimap<> containers equal. Otherwise
+	they are not equal. Data element set comparison does not rely on order
+	either.
+	\param m2 The other container to compare against.
+	\return Returns true if they are equal, false otherwise.
+	*/
+	bool operator==(const db_multimap<kdt, ddt, value_type_sub>& m2) const
+	{
+		
+		typedef typename self::const_iterator mm_itr_t;
+		
+		COMPARE_CHECK(m2)
+		
+		bool ret = false, retset = false;
+		size_t n1, n2;
+		int ret2;
+		const self &m1 = *this;
+		DbTxn *ptxn = NULL;
+		DbEnv *penv;
+		Db *pdb;
+		const char *dbfilename, *dbname;
+		const char *pname1, *pname2;
+		string name1, name2;
+		u_int32_t oflags;
+
+		verify_db_handles(m2);
+		pdb = this->get_db_handle();
+		penv = pdb->get_env();
+		try {
+			this->begin_txn();
+			if (m1.size() != m2.size()) {
+				ret = false;
+				this->commit_txn();
+				return ret;
+			}
+			BDBOP(pdb->get_dbname(&dbfilename, &dbname), ret2);
+			if (dbfilename == NULL)
+				pname1 = pname2 = NULL;
+			else {
+
+				this->construct_db_file_name(name1);
+				this->construct_db_file_name(name2);
+				// Make name2 different from name1.
+				name2.push_back('2');
+				pname1 = name1.c_str();
+				pname2 = name2.c_str();
+			}
+
+			Db *value_set_db = open_db(penv, 
+			    pname1, DB_BTREE, DB_CREATE, 0);
+
+			Db *value_set_db2 = open_db(penv, 
+			    pname2, DB_BTREE, DB_CREATE, 0);
+
+			db_set<ddt, value_type_sub> s1(value_set_db, penv), 
+				s2(value_set_db2, penv);
+
+			mm_itr_t i1, i11;
+			pair<mm_itr_t, mm_itr_t> resrg1, resrg2;
+			for (i1 = m1.begin(); 
+			    i1 != m1.end();
+			    i1 = resrg1.second) {
+				
+				resrg1 = m1.equal_range_N(i1->first, n1);
+				resrg2 = m2.equal_range_N(i1->first, n2);
+				if (n1 != n2) {
+					ret = false;
+					retset = true;
+					break;
+				}
+					
+				if (n2 == 1 && !(resrg2.first->second == 
+				    resrg1.first->second)) {
+					ret = false;
+					retset = true;
+					break;
+				}
+				
+				for (i11 = resrg1.first; i11 != resrg1.second;
+				    ++i11) 
+					s1.insert(i11->second);
+
+				for (i11 = resrg2.first; i11 != resrg2.second;
+				    ++i11)
+					s2.insert(i11->second);
+				if (!(s1 == s2)) {
+					ret = false;
+					retset = true;
+					break;
+				}
+				s1.clear();
+				s2.clear();
+
+				// Skip all equal keys in the range.
+				
+				
+			} // for
+
+			if (!retset) // Care: there are breaks in the for loop.
+				ret = true;
+
+			close_db(value_set_db);
+			close_db(value_set_db2);
+
+			ptxn = this->current_txn();
+			BDBOP(penv->get_open_flags(&oflags), ret2);
+			// The transaction handle in CDS is not a real 
+			// transaction.
+			if (oflags & DB_INIT_CDB)
+				ptxn = NULL;
+			if (name1.length() > 0)
+				BDBOP2(penv->dbremove(ptxn, name1.c_str(), 
+				    NULL, 0), ret2, this->abort_txn());
+			if (name2.length() > 0)
+				BDBOP2(penv->dbremove(ptxn, name2.c_str(), 
+				    NULL, 0), ret2, this->abort_txn());
+
+			this->commit_txn();
+			return ret;
+
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+	// Now that m1 and m2 has the same number of unique elements and all 
+	// elements of m1 are in m2, thus there can be no element of m2 that
+	// dose not belong to m1, so we won't verify each element of m2 are
+	// in m1.
+	//
+		
+	} // operator==
+
+	/// Container unequality comparison operator.
+	/// \param m2 The container to compare against.
+	/// \return Returns false if equal, true otherwise.
+	bool operator!=(const db_multimap<kdt, ddt, value_type_sub>& m2) const
+	{
+		return !this->operator==(m2);
+	}
+	////////////////////////////////////////////////////////////////
+	
+protected:
+	typedef ddt mapped_type;
+	typedef value_type_sub tkpair;
+	typedef int (*bt_compare_fcn_t)(Db *db, const Dbt *dbt1, 
+	    const Dbt *dbt2);
+
+	friend class db_map_iterator<kdt, _DB_STL_set_value<kdt>, 
+	    value_type_sub>;
+	friend class db_map_iterator<kdt, ddt, value_type_sub>;
+
+	db_multimap(BulkRetrievalOption &opt) : base(opt){}
+private:
+	value_type_sub operator[] (const key_type& x)
+	{
+		THROW(NotSupportedException, ("db_multimap<>::operator[]"));
+	}
+
+	value_type_sub operator[] (const key_type& x) const
+	{
+		THROW(NotSupportedException, ("db_multimap<>::operator[]"));
+		
+	}
+	
+	virtual const char* verify_config(Db*dbp, DbEnv* envp) const
+	{
+		DBTYPE dbtype;
+		u_int32_t oflags, sflags;
+		int ret;
+		const char *err = NULL;
+
+		err = db_container::verify_config(dbp, envp);
+		if (err)
+			return err;
+
+		BDBOP(dbp->get_type(&dbtype), ret);
+		BDBOP(dbp->get_open_flags(&oflags), ret);
+		BDBOP(dbp->get_flags(&sflags), ret);
+
+		if (dbtype != DB_BTREE && dbtype != DB_HASH)
+			err = 
+"wrong database type, only DB_BTREE and DB_HASH allowed for db_map<> class";
+		if (oflags & DB_TRUNCATE)
+			err = 
+"do not specify DB_TRUNCATE flag to create a db_map<> object";
+
+		// Can't go without no dup or dupsort flag set.
+		if (!((sflags & DB_DUP) || (sflags & DB_DUPSORT)))
+			err = 
+"db_multimap<> can not be backed by database not permitting duplicate keys";
+		
+		if (sflags & DB_RECNUM)
+			err = "no DB_RECNUM flag allowed in db_map<>";
+		
+		return err;
+		
+	}
+
+	inline void copy_db(db_multimap<kdt, ddt, value_type_sub> &x)
+	{	 
+
+		// Make sure clear can succeed if there are cursors 
+		// open in other threads.
+		this->clear(false);
+		insert(x.begin(), x.end());
+		
+	}
+
+};// db_multimap<>
+//@} //dbstl_containers
+END_NS
+
+#endif // !_DB_STL_DB_MAP_H_
diff --git a/stl/dbstl_resource_manager.cpp b/stl/dbstl_resource_manager.cpp
new file mode 100644
index 0000000..05d321e
--- /dev/null
+++ b/stl/dbstl_resource_manager.cpp
@@ -0,0 +1,1039 @@
+/*-
+ * See the file LICENSE for redistribution information.
+ *
+ * Copyright (c) 2009 Oracle.  All rights reserved.
+ *
+ * $Id$
+ */
+
+#include <assert.h>
+#include <utility>
+
+#include "dbstl_resource_manager.h"
+#include "dbstl_exception.h"
+#include "dbstl_dbc.h"
+
+START_NS(dbstl)
+
+typedef struct {
+	time_t	tv_sec;				/* seconds */
+	long	tv_nsec;			/* nanoseconds */
+} db_timespec;
+
+extern "C"{
+void __os_id (DB_ENV *, pid_t *, db_threadid_t*);
+void __os_gettime(ENV *env, db_timespec *tp, int monotonic);
+}
+
+using std::pair;
+using std::make_pair;
+
+// Static data member definitions.
+map<Db*, size_t> ResourceManager::open_dbs_;
+map<DbEnv*, size_t> ResourceManager::open_envs_;
+set<DbstlGlobalInnerObject *> ResourceManager::glob_objs_;
+set<Db *> ResourceManager::deldbs; 
+set<DbEnv *> ResourceManager::delenvs; 
+
+DbEnv * ResourceManager::mtx_env_ = NULL;
+db_mutex_t ResourceManager::mtx_handle_ = 0;
+db_mutex_t ResourceManager::mtx_globj_ = 0;
+
+#ifdef TLS_DEFN_MODIFIER
+template <Typename T> TLS_DEFN_MODIFIER T *TlsWrapper<T>::tinst_ = NULL;
+#elif defined(HAVE_PTHREAD_TLS)
+static pthread_once_t once_control_ = PTHREAD_ONCE_INIT;
+template <Typename T>
+pthread_key_t TlsWrapper<T>::tls_key_;
+
+template<Typename T>
+void tls_init_once(void) {
+	pthread_key_create(&TlsWrapper<T>::tls_key_, NULL);
+}
+
+template<Typename T>
+TlsWrapper<T>::TlsWrapper()
+{
+	pthread_once(&once_control_, tls_init_once<T>);
+}
+#else
+#error "No suitable thread-local storage model configured"
+#endif
+
+int ResourceManager::global_lock(db_mutex_t dbcontainer_mtx)
+{
+	int ret;
+
+	ret = mtx_env_->mutex_lock(dbcontainer_mtx);
+	dbstl_assert(ret == 0);
+	return 0;
+}
+
+int ResourceManager::global_unlock(db_mutex_t dbcontainer_mtx)
+{
+	int ret;
+
+	ret = mtx_env_->mutex_unlock(dbcontainer_mtx);
+	dbstl_assert(ret == 0);
+	return 0;
+}
+
+u_int32_t dbstl_strlen(const char *str)
+{
+	return (u_int32_t)strlen(str);
+}
+
+void dbstl_strcpy(char *dest, const char *src, size_t num)
+{
+	strncpy(dest, src, num);
+}
+
+int dbstl_strncmp(const char *s1, const char *s2, size_t num)
+{
+	return strncmp(s1, s2, num);
+}
+
+int dbstl_wcsncmp(const wchar_t *s1, const wchar_t *s2, size_t num)
+{
+	return wcsncmp(s1, s2, num);
+}
+
+int dbstl_strcmp(const char *s1, const char *s2)
+{
+	return strcmp(s1, s2);
+}
+
+int dbstl_wcscmp(const wchar_t *s1, const wchar_t *s2)
+{
+	return wcscmp(s1, s2);
+}
+
+u_int32_t dbstl_wcslen(const wchar_t *str)
+{
+	return (u_int32_t)wcslen(str);
+}
+
+void dbstl_wcscpy(wchar_t *dest, const wchar_t *src, size_t num)
+{
+	wcsncpy(dest, src, num);
+}
+
+// This function should be called in a single thread inside a process, before
+// any use of dbstl. We don't want to rely on platform dependent mutex API,
+// so we defer the synchronization to users.
+void ResourceManager::global_startup()
+{
+	int ret;
+	db_timespec tnow;
+
+	if (mtx_env_ == NULL) {
+		mtx_env_ = new DbEnv(DB_CXX_NO_EXCEPTIONS);
+		// Set cache size to 32k, to save space.
+		BDBOP(mtx_env_->set_cachesize(0, 32 * 1024, 1), ret);
+		BDBOP(mtx_env_->mutex_set_max(DBSTL_MAX_MTX_ENV_MUTEX), ret);
+		BDBOP2(mtx_env_->open(NULL, DB_PRIVATE | DB_CREATE, 0777),
+		    ret, mtx_env_->close(0));
+		BDBOP2(mtx_env_->mutex_alloc(DB_MUTEX_PROCESS_ONLY,
+		    &mtx_handle_), ret, mtx_env_->mutex_free(mtx_handle_));
+		BDBOP2(mtx_env_->mutex_alloc(DB_MUTEX_PROCESS_ONLY,
+		    &mtx_globj_), ret, mtx_env_->mutex_free(mtx_globj_));
+		__os_gettime(NULL, &tnow, 0);
+		srand((unsigned int)tnow.tv_sec);
+	}
+
+}
+
+ResourceManager::ResourceManager(void)
+{
+
+	// Initialize process wide dbstl settings. If there are multiple 
+	// threads, the global_startup should be called in a single thread 
+	// before any use of dbstl.
+	global_startup();
+}
+
+void ResourceManager::close_db(Db *pdb)
+{
+	bool berase = false;
+
+	if (pdb == NULL)
+		return;
+	db_csr_map_t::iterator itr = all_csrs_.find(pdb);
+	if (itr == all_csrs_.end())
+		return;
+
+	this->close_db_cursors(pdb);
+
+	delete all_csrs_[pdb];
+	all_csrs_.erase(itr);
+	pdb->close(0);
+	set<Db *>::iterator itrdb = deldbs.find(pdb);
+	// If new'ed by open_db, delete it.
+	if (itrdb != deldbs.end()) {
+		delete *itrdb;
+		berase = true;
+	}
+
+	global_lock(mtx_handle_);
+	open_dbs_.erase(pdb);
+	if (berase)
+		deldbs.erase(itrdb);
+
+	global_unlock(mtx_handle_);
+}
+
+void ResourceManager::close_all_db_envs()
+{
+	u_int32_t oflags;
+	int ret;
+	size_t txnstk_sz;
+
+	global_lock(mtx_handle_);
+	for (map<DbEnv*, size_t>::iterator i = open_envs_.begin();
+	    i != open_envs_.end(); ++i) {
+		BDBOP(i->first->get_open_flags(&oflags), ret);
+		txnstk_sz = env_txns_[i->first].size();
+		if (oflags & DB_INIT_CDB) {
+			assert(txnstk_sz == 1);
+			BDBOP(env_txns_[i->first].top()->commit(0), ret);
+		} else
+			assert(txnstk_sz == 0);
+
+		i->first->close(0);
+	}
+
+	// Delete DbEnv objects new'ed by dbstl.
+	set<DbEnv *>::iterator itr2 = delenvs.begin(); 
+	for (; itr2 != delenvs.end(); ++itr2)
+		delete *itr2;
+
+	delenvs.clear();
+	env_txns_.clear();
+	open_envs_.clear();
+	global_unlock(mtx_handle_);
+}
+
+void ResourceManager::close_db_env(DbEnv *penv)
+{
+	u_int32_t oflags;
+	int ret;
+	size_t txnstk_sz;
+	bool berase = false;
+
+	if (penv == NULL)
+		return;
+	map<DbEnv *, txnstk_t>::iterator itr = env_txns_.find(penv);
+	if (itr == env_txns_.end())
+		return;
+	BDBOP(penv->get_open_flags(&oflags), ret);
+	txnstk_sz = itr->second.size();
+	if (oflags & DB_INIT_CDB) {
+		assert(txnstk_sz == 1);
+		BDBOP(itr->second.top()->commit(0), ret);
+	} else
+		assert(txnstk_sz == 0);
+	env_txns_.erase(itr);
+	penv->close(0);
+
+	set<DbEnv *>::iterator itrdb = delenvs.find(penv);
+	// If new'ed by open_db, delete it.
+	if (itrdb != delenvs.end()) {
+		delete penv;
+		berase = true;
+	}
+
+	global_lock(mtx_handle_);
+	open_envs_.erase(penv);
+	if (berase)
+		delenvs.erase(itrdb);
+	global_unlock(mtx_handle_);
+}
+
+void ResourceManager::close_all_dbs()
+{
+	map<Db *, size_t>::iterator itr;
+	set<Db *>::iterator itr2;
+	Db *pdb;
+
+	global_lock(mtx_handle_);
+	for (itr = open_dbs_.begin(); itr != open_dbs_.end(); ++itr) {
+		pdb = itr->first;
+		this->close_db_cursors(pdb);
+
+		delete all_csrs_[pdb];
+		all_csrs_.erase(pdb);
+		pdb->close(0);
+	}
+
+	// Delete Db objects new'ed by dbstl.
+	for (itr2 = deldbs.begin(); itr2 != deldbs.end(); ++itr2)
+		delete *itr2;
+
+	deldbs.clear();
+	open_dbs_.clear();
+
+	global_unlock(mtx_handle_);
+}
+
+ResourceManager::~ResourceManager(void)
+{
+	u_int32_t oflags;
+	int ret;
+
+	global_lock(mtx_handle_);
+
+	for (map<Db*, size_t>::iterator i = open_dbs_.begin();
+	    i != open_dbs_.end(); ++i) {
+		this->close_db_cursors(i->first);
+		(i->second)--;
+		if (i->second == 0) {
+
+			delete all_csrs_[i->first]; // Delete the cursor set.
+			all_csrs_.erase(i->first);
+			i->first->close(0);
+
+			set<Db *>::iterator itrdb = deldbs.find(i->first);
+			// If new'ed by open_db, delete it.
+			if (itrdb != deldbs.end()) {
+				delete *itrdb;
+				deldbs.erase(itrdb);
+			}
+		}
+	}
+
+	for (map<DbEnv*, size_t>::iterator i = open_envs_.begin();
+	    i != open_envs_.end(); ++i) {
+		BDBOP(i->first->get_open_flags(&oflags), ret);
+		if (oflags & DB_INIT_CDB) {
+			assert(env_txns_[i->first].size() == 1);
+			BDBOP(env_txns_[i->first].top()->commit(0), ret);
+			env_txns_[i->first].pop();
+		}
+
+		(i->second)--;
+		if (i->second == 0) {
+			assert(env_txns_[i->first].size() == 0);
+			i->first->close(0);
+			set<DbEnv *>::iterator itrdb = delenvs.find(i->first);
+			// If new'ed by open_db, delete it.
+			if (itrdb != delenvs.end()) {
+				delete *itrdb;
+				delenvs.erase(itrdb);
+			}
+		}
+	}
+
+	global_unlock(mtx_handle_);
+
+	for (db_csr_map_t::iterator itr3 = all_csrs_.begin(); 
+	    itr3 != all_csrs_.end(); ++itr3)
+	{
+		// Delete the cursor set. Above code may not have a chance to
+		// delete this set because the db(itr3->first) was already 
+		// closed by another thread.
+		delete itr3->second; 
+	}
+	// Don't bother to clear all_csrs_ since it is being destructed.
+
+// Don't handle transactions, leave them alone, because autocommit
+// transactions must have been committed/aborted, and outside transactions
+// should be handled by user code, and if they are not handled yet,
+// the DbEnv::close will fail.
+// Only handle the transaction for CDS mode---an DB_TXN* handle is opened
+// at environment registration/creation by cdsgroup_begin, so we need to commit
+// that transaction.
+//
+}
+
+Db* ResourceManager::open_db (
+    DbEnv*penv, const char* filename, DBTYPE dbtype,
+    u_int32_t oflags, u_int32_t set_flags1, int mode, DbTxn* txn,
+    u_int32_t cflags, const char* dbname)
+{
+	int ret, ci = 0;
+	u_int32_t envf = 0, envoflags = 0;
+	DbTxn *ptxn = NULL;
+	Db *pdb = new Db(penv, cflags | DB_CXX_NO_EXCEPTIONS);
+
+	if (penv) {
+		BDBOP(penv->get_open_flags(&envoflags), ret);
+		BDBOP(penv->get_flags(&envf), ret);
+	}
+	if (set_flags1)
+		BDBOP(pdb->set_flags(set_flags1), ret);
+	// If no transaction is specified and we really need one, begin a
+	// transaction and commit it before return, we don't commit
+	// passed-in transaction.
+	//
+	if (penv && ((envf & DB_AUTO_COMMIT) ||
+	    (envoflags & DB_INIT_TXN)) && txn == 0){
+		ptxn = current_txn(penv);
+		BDBOP2(penv->txn_begin(ptxn, &txn, 0), ret, txn->abort());
+		ci = 1;
+	}
+	if (txn == NULL)
+		BDBOP2(pdb->open(txn, filename, dbname,
+		    dbtype, oflags, mode),
+		    ret, (pdb->close(0)));
+	else
+		BDBOP2(pdb->open(txn, filename, dbname,
+		    dbtype, oflags, mode),
+		    ret, (pdb->close(0), txn->abort()));
+	if (ci && txn)
+		BDBOP(txn->commit(0), ret);
+	global_lock(mtx_handle_);
+	open_dbs_.insert(make_pair(pdb, 1u));
+	pair<set<Db *>::iterator, bool> delinsret = deldbs.insert(pdb);
+	assert(delinsret.second);
+	global_unlock(mtx_handle_);
+	csrset_t *mycsrs = new csrset_t();
+	all_csrs_.insert(make_pair(pdb, mycsrs));
+
+	return pdb;
+}
+
+// Only called if the user does not supply an environment handle.
+DbEnv* ResourceManager::open_env(const char* env_home, u_int32_t set_flags1,
+    u_int32_t oflags, u_int32_t cachesize, int mode, u_int32_t cflags)
+{
+	int ret;
+
+	DbEnv *penv = new DbEnv(cflags | DB_CXX_NO_EXCEPTIONS);
+	if (set_flags1)
+		BDBOP(penv->set_flags(set_flags1, 1), ret);
+	BDBOP(penv->set_cachesize(0, cachesize, 1), ret);
+	BDBOP(penv->set_lk_max_lockers(2000), ret);
+	BDBOP(penv->set_lk_max_locks(2000), ret);
+	BDBOP(penv->set_lk_max_objects(2000), ret);
+	BDBOP2(penv->open(env_home, oflags, mode), ret, penv->close(0));
+
+	stack<DbTxn*> stk;
+	DbTxn *ptxn = NULL;
+	if (oflags & DB_INIT_CDB) {
+		BDBOP2(penv->cdsgroup_begin(&ptxn), ret, ptxn->commit(0));
+		stk.push(ptxn);
+	}
+
+	env_txns_.insert(make_pair(penv, stk));
+	global_lock(mtx_handle_);
+	open_envs_.insert(make_pair(penv, 1u));
+	delenvs.insert(penv);
+	global_unlock(mtx_handle_);
+	return penv;
+}
+
+DbTxn* ResourceManager::current_txn(DbEnv*env)
+{
+	if (env_txns_.count(env) <= 0)
+		return NULL;
+
+	stack<DbTxn*> &pstk = env_txns_[env];
+	return pstk.size() != 0 ? pstk.top() : NULL;
+}
+
+void ResourceManager::set_global_callbacks()
+{
+	DbstlElemTraits<char> * cstarinst = 
+	    DbstlElemTraits<char>::instance();
+	cstarinst->set_sequence_len_function(dbstl_strlen);
+	cstarinst->set_sequence_copy_function(dbstl_strcpy);
+	cstarinst->set_sequence_compare_function(dbstl_strcmp);
+	cstarinst->set_sequence_n_compare_function(dbstl_strncmp);
+
+	DbstlElemTraits<wchar_t> *wcstarinst = 
+	    DbstlElemTraits<wchar_t>::instance();
+	wcstarinst->set_sequence_copy_function(dbstl_wcscpy);
+	wcstarinst->set_sequence_len_function(dbstl_wcslen);
+	wcstarinst->set_sequence_compare_function(dbstl_wcscmp);
+	wcstarinst->set_sequence_n_compare_function(dbstl_wcsncmp);
+}
+
+ResourceManager* ResourceManager::instance()
+{
+	ResourceManager *pinst = NULL;
+#ifdef HAVE_PTHREAD_TLS
+	// Initialize the tls key.
+	pthread_once(&once_control_, tls_init_once<ResourceManager>);
+#endif
+
+	if ((pinst = TlsWrapper<ResourceManager>::get_tls_obj()) == NULL){
+		TlsWrapper<ResourceManager>::set_tls_obj(
+		    pinst = new ResourceManager());
+		register_global_object(pinst);
+		set_global_callbacks();
+	}
+	return pinst;
+}
+
+int ResourceManager::open_cursor(DbCursorBase *dcbcsr,
+    Db *pdb, int flags)
+{
+	u_int32_t oflags = 0;
+	int ret;
+
+	if (!pdb || !dcbcsr)
+		return 0;
+
+	csrset_t::iterator csitr;
+	Dbc* csr = NULL;
+	dcbcsr->set_owner_db(pdb);
+
+	DbTxn *ptxn = NULL;
+	DbTxn *ptxn2 = this->current_txn(pdb->get_env());
+	if (ptxn2) {
+		ptxn = ptxn2;
+		dcbcsr->set_owner_txn(ptxn);
+	}
+
+	if (pdb->get_env() != NULL){
+		ret = pdb->get_env()->get_open_flags(&oflags);
+		dbstl_assert(ret == 0);
+	}
+
+	// Call Dbc->cursor only if there is no active open cursor in the
+	// current thread, otherwise duplicate one from the existing cursor
+	// and use the locks already held in this thread.
+	//
+	csrset_t *pcsrset = NULL;
+	db_csr_map_t::iterator itrpcsrset = all_csrs_.find(pdb);
+	if (itrpcsrset == all_csrs_.end()) { // No such pair in current thread.
+		pcsrset = new csrset_t;
+		pair<db_csr_map_t::iterator, bool> insret0 = 
+		    all_csrs_.insert(make_pair(pdb, pcsrset));
+		assert(insret0.second);
+	} else
+		pcsrset = itrpcsrset->second;
+
+	assert(pcsrset != NULL);
+	if (pcsrset->size() == 0) {
+newcursor:
+		BDBOP2(pdb->cursor(ptxn, &csr, flags), ret,
+		    ((csr != NULL ? csr->close() : 1),
+		    this->abort_txn(pdb->get_env())));
+	} else {
+		// We have some open cursors, so try to dup from one. If we are
+		// in CDS mode, and trying to open a write cursor, we should
+		// duplicate from a write cursor.
+		csitr = pcsrset->begin();
+		Dbc *csr22 = (*csitr)->get_cursor();
+		assert(csr22 != NULL);
+		assert(!((oflags & DB_INIT_TXN) && (flags & DB_WRITECURSOR)));
+		// If opening a CDS write cursor, must find a write cursor
+		// to duplicate from.
+		if (((flags & DB_WRITECURSOR) != 0)) {
+			for (;csitr != pcsrset->end(); ++csitr) {
+				csr22 = (*csitr)->get_cursor();
+				if (((DBC*)csr22)->flags & DBC_WRITECURSOR) {
+					// No need to abortTxn on fail in CDS.
+					BDBOP2(csr22->dup(&csr, DB_POSITION),
+					     ret, csr->close());
+					goto done;
+				}
+			}
+			goto newcursor; // No write cursor, create a new one.
+
+		} else if (((oflags & DB_INIT_TXN) == 0) || 
+		    pdb->get_transactional() == 0) {
+			// We are opening a DS or CDS read cursor, or 
+			// opening a cursor in 
+			// a transactional environment from a database not 
+			// transactionally created.
+			BDBOP2(csr22->dup(&csr, DB_POSITION), ret,
+			    (csr->close(), this->abort_txn(pdb->get_env())));
+			goto done;
+		} else  {
+			// We are opening a transactional cursor, duplicate
+			// from a transactional one.
+			// We don't remove (close) the non-transactional ones,
+			// they are in use.
+			// Hold the locks already held in this thread,
+			// so need DB_POSITION flag.
+			//
+			DbTxn *ptxn3 = NULL;
+			DbCursorBase *dcbcursor = NULL;
+			csrset_t::iterator itr3, itr4;
+			int got_rg = 0;
+
+			// Opening a cursor in a transactional environment
+			// with no transaction specified. This should not
+			// happen in the first place.
+			if (ptxn == NULL)
+				THROW(InvalidArgumentException, ("DbTxn*",
+"Opening a cursor in a transactional environment but no transaction \
+is started specified"));
+			// When we check that there must be a valid transaction
+			// handle ptxn when opening a cursor in a
+			// transactional environment, the following code
+			// to delete cursors with no transaction
+			// is not required and never reached,
+			// but we will leave it there.
+			for (;csitr != pcsrset->end();) {
+				dcbcursor = *csitr;
+				ptxn3 = dcbcursor->get_owner_txn();
+				if (ptxn3 == NULL) {
+					BDBOP(dcbcursor->close(), ret);
+					if (!got_rg){
+						got_rg++;
+						itr3 = csitr;
+					}
+				} else if (got_rg) {
+					got_rg = 0;
+					itr4 = csitr;
+					pcsrset->erase(itr3, itr4);
+					csitr = pcsrset->begin();
+					continue;
+				}
+
+				if (ptxn3 == ptxn)  {
+					csr22 = dcbcursor->get_cursor();
+					BDBOP2(csr22->dup(&csr, DB_POSITION),
+					    ret, (csr->close(), this->
+					    abort_txn(pdb->get_env())));
+					goto done;
+				}
+				++csitr;
+
+			}
+			if (got_rg) {
+				pcsrset->erase(itr3, pcsrset->end());
+				got_rg = 0;
+			}
+
+			goto newcursor;
+
+		} // else oflags & DB_INIT_TXN
+	} // else pcsrset->size()
+done:
+	// Insert into current thread's db-cursor map and txn_csrs_ map,
+	// for later duplication.
+	//
+	dcbcsr->set_cursor(csr);
+	this->add_cursor(pdb, dcbcsr);
+	return 0;
+}
+
+void ResourceManager::add_cursor(Db* dbp, DbCursorBase* dcbcsr)
+{
+	if (!dbp || !dcbcsr)
+		return;
+	assert(dcbcsr->get_cursor() != NULL);
+
+	(all_csrs_[dbp])->insert(dcbcsr);
+	// Register to txncsrs_, we suppose current transaction is the context
+	// of this operation.
+	//
+	this->add_txn_cursor(dcbcsr, dbp->get_env());
+}
+
+// Close dbp's all open cursors opened in current thread, do not close
+// those of dbp opened in other threads, Db::truncate requires dbp's
+// all cursors of all threads should be closed, and it is user's duty
+// to make sure other threads all close dbp's cursor, because if we
+// close them here, it is also an error---multi-threaded access to the same
+// Dbc* cursor should be serialized, we can't serialize with user code
+// anyway.
+//
+size_t ResourceManager::close_db_cursors(Db* dbp1)
+{
+	int ret;
+	Db* dbp;
+	DbTxn *ptxn, *ptxn2;
+	csrset_t *pcset_txn;
+
+	if (dbp1 == NULL)
+		return 0;
+
+	dbp = dbp1;
+	db_csr_map_t::iterator itr0;
+	csrset_t::iterator itr;
+
+	itr0 = all_csrs_.find(dbp1);
+	if (itr0 == all_csrs_.end())
+		return 0;
+
+	csrset_t *pcset = itr0->second;
+
+	pcset_txn = NULL;
+	ptxn2 = ptxn = NULL;
+	size_t txncsr_sz = txn_csrs_.size();
+
+	for (itr = pcset->begin(), ret = 0; itr != pcset->end();
+	    ++itr, ret++) {
+
+		BDBOP((*itr)->close(), ret);
+		if (txncsr_sz > 0) {
+			if (pcset_txn == NULL || ptxn !=
+			    (ptxn2 = (*itr)->get_owner_txn())) {
+				ptxn = ptxn2 ? ptxn2 : (*itr)->get_owner_txn();
+				if (ptxn != NULL)
+					pcset_txn = txn_csrs_[ptxn];
+			}
+			if (pcset_txn)
+				pcset_txn->erase(*itr);
+		}
+
+	}
+
+	// Don't delete the pcset or itr0 because this dbp1 may be used
+	// by other containers in this thread.
+	pcset->clear();
+	// We don't delete the DbCursorBase object, it is still
+	// referenced by others.
+	return ret;
+}
+
+// Close the cursor of csr and remove the entry containing csr from
+// txn_csrs_ and all_csrs_.
+int ResourceManager::remove_cursor(DbCursorBase*csr,
+    bool remove_from_txncsrs)
+{
+	int ret;
+
+	if (csr == NULL)
+		return 0;
+	BDBOP(csr->close(), ret);
+
+	if (remove_from_txncsrs) {
+		DbTxn *ptxn = csr->get_owner_txn();
+		if (ptxn != NULL) {
+			txncsr_t::iterator itr = txn_csrs_.find(ptxn);
+			if (itr != txn_csrs_.end())
+				itr->second->erase(csr);
+		}
+	}
+
+	Db *pdb = csr->get_owner_db();
+	if (pdb != NULL)
+		all_csrs_[pdb]->erase(csr);
+
+	return ret;
+}
+
+/*
+ * Remove cursors opened in transaction txn's context, should be called before
+ * commiting/aborting a transaction.
+ * Note that here we should remove the cursor from all_csrs_ too,
+ * by calling remove_cursor() function.
+ */
+void ResourceManager::remove_txn_cursor(DbTxn* txn)
+{
+	int ret;
+
+	if (!txn)
+		return;
+
+	txncsr_t::iterator itr0;
+	csrset_t::iterator itr;
+	itr0 = txn_csrs_.find(txn);
+	if (itr0 == txn_csrs_.end())
+		return; // No cursor opened in this txn.
+
+	csrset_t *pcsrs = itr0->second;
+	DbCursorBase *csr;
+
+	// Remove(close and remove from csr registry) cursors
+	// opened in the transaction txn's context.
+	for (itr = pcsrs->begin(); itr != pcsrs->end(); ++itr) {
+		// This cursor should be closed now and removed
+		// from csr registry.
+		csr = *itr;
+		BDBOP(csr->close(), ret);
+		all_csrs_[csr->get_owner_db()]->erase(csr);
+	}
+
+	delete pcsrs;
+	// Erase csrs belonging to txn.
+	txn_csrs_.erase(itr0);
+}
+
+// Begin a new transaction from the specified environment env.
+// When outtxn is non-zero, it supports nested txn,
+// so the new transaction is started as a child transaction of the
+// current one, and we push it into env1's transaction stack;
+// Otherwise, we are starting an internal transaction for autocommit,
+// no new transaction will be started, but current transaction's reference
+// count will be incremented.
+DbTxn* ResourceManager::begin_txn(u_int32_t flags, DbEnv*env1, int outtxn)
+{
+	DbEnv *env = env1;
+	DbTxn *ptxn, *txn = NULL;
+	int ret;
+
+	if (!env1)
+		return NULL;
+
+	assert(env_txns_.count(env1) > 0);
+
+	stack<DbTxn*>&stk = env_txns_[env1];
+
+	// Not an outside transaction, so if there is transaction in stack,
+	// use it and increment its reference count.
+	if (outtxn == 0) {
+		// We have a transaction in stack, increment its reference
+		// count.
+		if (stk.size() > 0) {
+			txn = stk.top();
+			// The txn was created externally, now we internally
+			// use it, so the reference count is 2.
+			map<DbTxn *, size_t>::iterator itr12;
+			if ((itr12 = txn_count_.find(txn)) == txn_count_.end())
+				txn_count_.insert(make_pair(txn, 2u));
+			else
+				txn_count_[txn]++;
+		} else {
+	// Empty stack, create a transaction and set reference count to 1.
+			BDBOP(env->txn_begin(NULL, &txn, flags), ret);
+			stk.push(txn);
+			txn_count_[txn] = 1;// the first to use it
+			txn_csrs_.insert(make_pair(txn, new csrset_t()));
+		}
+
+	} else { // Creating a transaction by user, used outside of dbstl.
+		ptxn = stk.size() > 0 ? stk.top() : NULL;
+
+		BDBOP(env->txn_begin(ptxn, &txn, flags), ret);
+
+		// txn now is the current txn
+		stk.push(txn);
+		txn_csrs_.insert(make_pair(txn, new csrset_t()));
+	}
+
+	return txn;
+}
+
+void ResourceManager::commit_txn(DbEnv *env, u_int32_t flags)
+{
+	int ret;
+	DbTxn *ptxn;
+
+	if (!env)
+		return;
+
+	assert(env_txns_.count(env) > 0);
+	stack<DbTxn*> &stk = env_txns_[env];
+	ptxn = stk.top();
+	assert(ptxn != NULL);
+	size_t txncnt = txn_count_[ptxn];
+
+	if (txncnt > 1) // used internally
+		txn_count_[ptxn]--;
+	else {
+		txn_count_.erase(ptxn);
+		this->remove_txn_cursor(ptxn);
+		stk.pop();
+		BDBOP(ptxn->commit(flags), ret);
+
+	}
+
+}
+
+void ResourceManager::commit_txn(DbEnv *env, DbTxn *txn, u_int32_t flags)
+{
+	DbTxn *ptxn = NULL;
+	int ret;
+
+	if (env == NULL || txn == NULL)
+		return;
+
+	stack<DbTxn*> &stk = env_txns_[env];
+	while (stk.size() > 0 && (ptxn = stk.top()) != txn) {
+		stk.pop();
+		txn_count_.erase(ptxn);// may be in the txn_count_ map
+		this->remove_txn_cursor(ptxn);
+		// Child txns could be committed by parent txn, but c++ API 
+		// can't delete the new'ed child txns when committing the 
+		// parent txn, so have to commit them explicitly.
+		ptxn->commit(flags);
+	}
+	if (stk.size() == 0)
+		THROW(InvalidArgumentException, (
+		    "No such transaction created by dbstl"));
+	else {
+		stk.pop();
+		txn_count_.erase(txn);// may be in the txn_count_ map
+		this->remove_txn_cursor(txn);
+		if (ptxn){
+			BDBOP(ptxn->commit(flags), ret);
+		} else // could never happen
+			THROW(InvalidArgumentException, (
+			    "No such transaction created by dbstl"));
+
+	}
+}
+
+void ResourceManager::abort_txn(DbEnv *env, DbTxn *txn)
+{
+	int ret;
+	DbTxn *ptxn = NULL;
+	u_int32_t oflags;
+
+	if (env == NULL || txn == NULL)
+		return;
+
+	BDBOP (env->get_open_flags(&oflags), ret);
+	stack<DbTxn*> &stk = env_txns_[env];
+	while (stk.size() > 0 && (ptxn = stk.top()) != txn) {
+		txn_count_.erase(ptxn);// may be in the txn_count_ map
+		this->remove_txn_cursor(ptxn);
+		stk.pop();
+		// Child txns could be aborted by parent txn, but c++ API 
+		// can't delete the new'ed child txns when aborting the 
+		// parent txn, so have to abort them explicitly.
+		ptxn->abort();
+	}
+	if (stk.size() == 0)
+		THROW(InvalidArgumentException, (
+		    "No such transaction created by dbstl"));
+	else {
+		stk.pop();
+		txn_count_.erase(txn);// may be in the txn_count_ map
+		this->remove_txn_cursor(txn);
+		if (ptxn){
+			if ((oflags & DB_INIT_CDB) == 0)
+				BDBOP(ptxn->abort(), ret);
+		} else // could never happen
+			THROW(InvalidArgumentException, (
+			    "No such transaction created by dbstl"));
+
+	}
+}
+
+// Abort current txn, close/remove its cursors and reference count.
+void ResourceManager::abort_txn(DbEnv*env)
+{
+	int ret;
+	DbTxn *ptxn;
+	u_int32_t oflags;
+
+	if (!env)
+		return;
+	env_txns_t::iterator itr(env_txns_.find(env));
+	if (itr == env_txns_.end())
+		return;
+
+	stack<DbTxn*> &stk = itr->second;
+	if (stk.size() == 0)
+		return;
+	ptxn = stk.top();
+	if (ptxn == NULL)
+		return;
+	this->remove_txn_cursor(ptxn);
+	BDBOP (env->get_open_flags(&oflags), ret);
+
+	// Transactions handles created via cdsgroup_begin can not be aborted
+	// because they are not really transactions, they just borrow the
+	// DB_TXN structure to store a locker id.
+	if ((oflags & DB_INIT_CDB) == 0) 
+		BDBOP(ptxn->abort(), ret);
+	txn_count_.erase(ptxn);
+	stk.pop();
+}
+
+DbTxn* ResourceManager::set_current_txn_handle(DbEnv *env, DbTxn *newtxn)
+{
+	assert(env_txns_.count(env) > 0);
+	stack<DbTxn*> &stk = env_txns_[env];
+	DbTxn *ptxn = stk.top();
+	stk.pop();
+	stk.push(newtxn);
+	return ptxn;
+}
+
+void ResourceManager::add_txn_cursor(DbCursorBase *dcbcsr, DbEnv *env)
+{
+	if (!env || !dcbcsr)
+		return;
+
+	DbTxn *ptxn = this->current_txn(env);
+	if (ptxn == NULL)
+		return;
+
+	u_int32_t oflags;
+	int ret;
+
+	BDBOP(env->get_open_flags(&oflags), ret);
+	if ((oflags & DB_INIT_TXN) == 0)
+		return;
+
+	txncsr_t::iterator itr;
+	csrset_t *pset;
+
+	itr = txn_csrs_.find(ptxn);
+	pair<txncsr_t::iterator, bool> insret;
+
+	if (itr == txn_csrs_.end()) {
+		insret = txn_csrs_.insert(make_pair(ptxn, new csrset_t()));
+		assert(insret.second);
+		itr = insret.first;
+	}
+	pset = itr->second;
+	pset->insert(dcbcsr);
+}
+
+void ResourceManager::register_db(Db*pdb1)
+{
+	if (!pdb1)
+		return;
+	global_lock(mtx_handle_);
+	if (open_dbs_.count(pdb1) == 0)
+		open_dbs_.insert(make_pair(pdb1, 1u));
+	else
+		open_dbs_[pdb1]++;
+	global_unlock(mtx_handle_);
+	csrset_t *pcsrset = new csrset_t();
+	pair<db_csr_map_t::iterator, bool> insret = all_csrs_.insert(
+	    make_pair(pdb1, pcsrset));
+	if (!insret.second)
+		delete pcsrset;
+
+}
+
+void ResourceManager::register_db_env(DbEnv*env1)
+{
+	u_int32_t oflags = 0;
+	DbTxn *ptxn = NULL;
+	int ret;
+
+	if (!env1)
+		return;
+
+	stack<DbTxn*> stk;
+	BDBOP(env1->get_open_flags(&oflags), ret);
+
+	if (oflags & DB_INIT_CDB) {
+		env1->cdsgroup_begin(&ptxn);
+		stk.push(ptxn);
+	}
+
+	env_txns_.insert(make_pair(env1, stk));
+
+	global_lock(mtx_handle_);
+	if (open_envs_.count(env1) == 0)
+		open_envs_.insert(make_pair(env1, 1u));
+	else
+		open_envs_[env1]++;
+	global_unlock(mtx_handle_);
+}
+
+// Delete registered DbstlGlobalInnerObject objects.
+void ResourceManager::global_exit()
+{
+	set<DbstlGlobalInnerObject *>::iterator itr;
+	global_lock(mtx_globj_);
+	for (itr = glob_objs_.begin(); itr != glob_objs_.end(); ++itr)
+		delete *itr;
+	global_unlock(mtx_globj_);
+
+	mtx_env_->mutex_free(mtx_globj_);
+	mtx_env_->mutex_free(mtx_handle_);
+	delete mtx_env_;
+}
+
+void ResourceManager::register_global_object(DbstlGlobalInnerObject *gio)
+{
+	global_lock(mtx_globj_);
+	glob_objs_.insert(gio);
+	global_unlock(mtx_globj_);
+}
+
+END_NS
diff --git a/stl/dbstl_resource_manager.h b/stl/dbstl_resource_manager.h
new file mode 100644
index 0000000..6bca540
--- /dev/null
+++ b/stl/dbstl_resource_manager.h
@@ -0,0 +1,355 @@
+/*-
+ * See the file LICENSE for redistribution information.
+ *
+ * Copyright (c) 2009 Oracle.  All rights reserved.
+ *
+ * $Id$
+ */
+
+#ifndef _DB_STL_RESOURCE_MANAGER_H__
+#define _DB_STL_RESOURCE_MANAGER_H__
+
+#include <map>
+#include <vector>
+#include <stack>
+#include <set>
+
+#include "dbstl_common.h"
+#include "dbstl_inner_utility.h"
+
+START_NS(dbstl)
+
+class DbCursorBase;
+using std::map;
+using std::multimap;
+using std::set;
+using std::stack;
+
+///////////////////////////////////////////////////////////////////////
+/////////////////////////////////////////////////////////////////////////
+//
+// ResourceManager class definition
+//
+// This class manages all the Berkeley DB handles and their mapping
+// relationship. When it's only thread-specific instance is destructed,
+// these handles are automatically closed in the correct order (the db and
+// dbenv handles will be closed when the last thread using the handles in
+// the process is destructed).
+//
+// The Db* and DbEnv* handles are process-wide global, they can be shared
+// among multithreads, so they are stored into a static stl map, and access
+// to the two map objects (open_dbs_ & open_envs_) is protected by a process
+// wide mutex because few stl implementations support multithreaded access.
+// We use reference counting in the two map objects to make sure each handle
+// is closed when the last thread using it exits. Each thread sharing the
+// handle should call ResourceManager::register_db/dbenv to tell DBSTL that
+// it will use the handle, otherwise the handle may be closed prematurely.
+//
+// The transaction and cursor handles are thread specific. They are stored
+// into stl containers and each instance of the ResourceManager is stored
+// into thread local storage(TLS) of each thread. Thus the DB STL containers
+// are thread safe.
+//
+
+// This map contains cursors of all open databases opened in the same thread.
+// We can only duplicate a cursor of the same database; We don't allow sharing
+// Berkeley DB cursor handles across multiple threads, each thread needs to
+// open their own cursor handle;
+//
+typedef map<Db *, set<dbstl::DbCursorBase *> *> db_csr_map_t;
+
+// The set of cursors that belong to a db handle or a transaction.
+typedef set<dbstl::DbCursorBase *> csrset_t;
+// The cursors opened in each transaction.
+typedef map<DbTxn *, set<DbCursorBase *> *> txncsr_t;
+
+// This stack contains the transactions started in current thread. Each
+// transaction is the child transaction of the one under it in the stack.
+//
+// We support nested transactions for those created by the dbstl
+// users, but still keep reference counting for dbstl internally
+// created transactions so that the autocommit methods are really
+// autocommit with least overhead (nested transactions are overheads). The
+// way we keep both nested transaction and reference counting to internal
+// transactions in the same stack is:
+// 1. When creating an external transaction, look at the stack top, if there
+// is a transaction, it must be an external one too, so use it as the parent
+// transaction to create the external transaction.
+// 2. When creating an internal transaction, look at the stack top, if there
+// is one, call it T, look for its the reference counting, if there is a
+// reference count for it, T is an internal one, so we increment its
+// reference count; Otherwise, T is an external one, and according to the DB
+// autocommit semantics, this function should be in T's context, so we
+// simply use T and add it to the reference counting structure, and set its
+// reference count to 2.
+//
+// We don't support expanding a transaction across multiple threads,
+// because there are many restrictions to doing so, making it meaningless.
+//
+typedef stack<DbTxn *> txnstk_t;
+typedef map<DbEnv *, txnstk_t> env_txns_t;
+
+#ifdef WIN32
+#pragma warning( push )
+#pragma warning( disable:4251 )
+#endif
+// This class is used to wrap a ResourceManager instance pointer, so that
+// each thread has its own ResourceManager singleton.
+
+#ifdef TLS_DECL_MODIFIER
+template <Typename T>
+class TlsWrapper
+{
+public:
+	static T *get_tls_obj()
+	{
+		return tinst_;
+	}
+
+	static void set_tls_obj(T *objp)
+	{
+		tinst_ = objp;
+	}
+
+private:
+	TlsWrapper(){}
+
+	// Thread local pointer to the instance of type T.
+	static TLS_DECL_MODIFIER T *tinst_;
+}; // TlsWrapper<>
+
+#elif defined(HAVE_PTHREAD_TLS)
+template <Typename T>
+class TlsWrapper
+{
+public:
+	static T *get_tls_obj()
+	{
+		return static_cast<T*>(pthread_getspecific(tls_key_));
+	}
+
+	static void set_tls_obj(T *objp)
+	{
+		pthread_setspecific(tls_key_, objp);
+	}
+
+	// Friend declarations don't work portably, so we have to declare 
+	// tls_key_ public.
+	static pthread_key_t tls_key_;
+private:
+	TlsWrapper();
+
+}; // TlsWrapper<>
+
+#else
+#error "A multi-threaded build of STL for Berkeley DB requires thread local storage.  None is configured."
+#endif
+
+class _exported ResourceManager : public DbstlGlobalInnerObject
+{
+private:
+
+	ResourceManager(void);
+	// open_dbs_ & open_envs_ are shared among threads, protected by
+	// ghdl_mtx;
+	static map<Db *, size_t> open_dbs_;
+	static map<DbEnv *, size_t>open_envs_;
+
+	// Transaction stack of all environments. Use a stack to allow nested
+	// transactions. The transaction at the top of the stack is the
+	// current active transaction.
+	//
+	env_txns_t env_txns_;
+
+	// Cursors opened in a corresponding transaction context. When
+	// committing or aborting a transaction, first close all open cursors.
+	//
+	txncsr_t txn_csrs_;
+
+	// If in container X, its methods X::A and X::B both call begin and
+	// commit transaction. X::A calls X::B after it's begin transaction
+	// call, then X::B will commit the transaction prematurally. To avoid
+	// will commit the only transaction prematurally, to avoid this, we use
+	// this, we use this map to record each transaction's reference count.
+	// Each begin/commit_txn() will increment/decrement the reference
+	// count, when reference count goes to 0, the transaction is committed.
+	// Abort_txn will unconditionally abort the transaction.
+	//
+	map<DbTxn *, size_t> txn_count_;
+
+	// Contains the cursors opened in the current thread for each database,
+	// So that we can close them in the right way, freeing any Berkeley DB
+	// handles before exiting.
+	//
+	db_csr_map_t all_csrs_;
+
+	// Remove cursors opened in the transaction txn's context, should be
+	// called before commiting or aborting a transaction.
+	//
+	void remove_txn_cursor(DbTxn *txn);
+
+	// Add a cursor to the current transaction's set of open cursors.
+	void add_txn_cursor(DbCursorBase *dcbcsr, DbEnv *env);
+
+	// The environment mtx_env_ and mtx_handle_ are used for synchronizing
+	// multiple threads' access to open_dbs_ and open_envs_ and glob_objs_.
+	// They are discarded when program exits, no deallocation/release
+	// is done.
+	static DbEnv *mtx_env_;
+	static db_mutex_t mtx_handle_;
+	static db_mutex_t mtx_globj_;
+	static set<DbstlGlobalInnerObject *> glob_objs_;
+
+	// This set stores db handles that are new'ed by open_db, and thus 
+	// should be deleted after this db is closed automatically by dbstl.
+	// If a db is new'ed and created by user without using open_db, users
+	// should delete it.
+	static set<Db *> deldbs; 
+	static set<DbEnv *> delenvs; // Similar to deldbs, works with open_envs.
+	static void set_global_callbacks();
+public:
+	
+	// This function should be called in a single thread inside a process, 
+	// before any use of dbstl.
+	static void global_startup();
+	// Delete registered DbstlGlobalInnerObject objects.
+	static void global_exit();
+	static void register_global_object(DbstlGlobalInnerObject *gio);
+	static DbEnv *get_mutex_env() { return mtx_env_; }
+	// Lock mtx_handle_, if it is 0, allocate it first.
+	static int global_lock(db_mutex_t dbcontainer_mtx);
+	static int global_unlock(db_mutex_t dbcontainer_mtx);
+	// Close pdb regardless of its reference count, users must make sure
+	// pdb is not used by others before calling this method. We can't
+	// close by reference count in this method, otherwise when the thread
+	// exits pdb's reference count is decremented twice.
+	void close_db(Db *pdb);
+
+	// Close all db handles regardless of reference count, used to clean up
+	// the calling thread's ResourceManager singleton.
+	void close_all_dbs();
+
+	// Close specified db env handle and remove it from resource manager.
+	void close_db_env(DbEnv *penv);
+
+	// Close and remove all db env registered in the resource manager.
+	// Used to clean up the calling thread's ResourceManager singleton.
+	void close_all_db_envs();
+
+	// Begin a new transaction in the specified environment. When outtxn
+	// is non-zero support nested transactions - the new transaction will
+	// be started as a child of the current transaction. If outtxn is 0
+	// we are starting an internal transaction for autocommit, no new
+	// transaction will be started, but the current transaction's
+	// reference count will be incremented if it already has a reference
+	// count; otherwise, it was created by user, and we simply use this
+	// transaction, set its reference count to 2.
+	//
+	// This function is called by both containers to begin an internal
+	// transaction for autocommit, and by db stl users to begin an
+	// external transaction.
+	//
+	DbTxn *begin_txn(u_int32_t flags/* flags for DbEnv::txn_begin */,
+	    DbEnv *env, int outtxn);
+
+	// Decrement reference count if it exists and if it goes to 0, commit
+	// current transaction T opened in env;
+	// If T has no reference count(outside transaction), simply find
+	// it by popping the stack and commit it.
+	//
+	// This function is called by db_container to commit a transaction
+	// for auto commit, also can be called by db stl user to commit
+	// an external explicit transaction.
+	//
+	void commit_txn(DbEnv *env, u_int32_t flags = 0);
+
+	// Commit specified transaction txn: find it by popping the stack,
+	// discard all its child transactions and commit it.
+	//
+	// This function is called by dbstl user to commit an external
+	// explicit transaction.
+	//
+	void commit_txn(DbEnv *env, DbTxn *txn, u_int32_t flags = 0);
+
+	// Abort current transaction of the environment.
+	//
+	void abort_txn(DbEnv *env);
+
+	// Abort specified transaction: find it by popping the stack, discard
+	// all its child transactions and abort it.
+	//
+	// This function is called by dbstl user to abort an external
+	// explicit transaction.
+	//
+	void abort_txn(DbEnv *env, DbTxn *txn);
+
+	// Set env's current transaction handle. The original transaction
+	// handle is returned without aborting or commiting. This API can be
+	// used to share a transaction handle among multiple threads.
+	DbTxn* set_current_txn_handle(DbEnv *env, DbTxn *newtxn);
+
+	// Register a Db handle. This handle and handles opened in it
+	// will be closed by ResourceManager, so application code must not
+	// try to close or delete it. Users can configure the handle before
+	// opening the Db and then register it via this function.
+	//
+	void register_db(Db *pdb1);
+
+	// Register a DbEnv handle. This handle and handles opened in it
+	// will be closed by ResourceManager, so application code must not try
+	// to close or delete it. Users can configure the handle before
+	// opening the Environment and then register it via this function.
+	//
+	void register_db_env(DbEnv *env1);
+
+	// Helper function to open a database and register it into
+	// ResourceManager.
+	// Users can set the create flags, open flags, db type, and flags
+	// needing to be set before open.
+	//
+	Db* open_db (DbEnv *penv, const char *filename, DBTYPE dbtype,
+	    u_int32_t oflags, u_int32_t set_flags, int mode = 0644,
+	    DbTxn* txn = NULL, u_int32_t cflags = 0,
+	    const char *dbname = NULL);
+
+	// Helper function to open a dbenv and register it into
+	// ResourceManager.
+	// Users can set the create flags, open flags, db type, and flags
+	// needing to be set before open.
+	//
+	DbEnv *open_env(const char *env_home, u_int32_t set_flags,
+	    u_int32_t oflags = DB_CREATE | DB_INIT_MPOOL,
+	    u_int32_t cachesize = 4 * 1024 * 1024, int mode = 0644,
+	    u_int32_t cflags = 0/* Flags for DbEnv constructor. */);
+
+	static ResourceManager *instance();
+
+	// Release all registered resource in the right order.
+	virtual ~ResourceManager(void);
+
+	// Return current transaction of environment env, that is, the one on
+	// the transaction stack top, the active one.
+	//
+	DbTxn *current_txn(DbEnv *env);
+
+	// Open a Berkeley DB cursor.
+	//
+	int open_cursor(DbCursorBase *dcbcsr, Db *pdb, int flags = 0);
+
+	// Add a db-cursor mapping.
+	void add_cursor(Db *dbp, DbCursorBase *csr);
+
+	// Close all cursors opened in the database.
+	size_t close_db_cursors(Db *dbp1);
+
+	// Close and remove a cursor from ResourceManager.
+	//
+	int remove_cursor(DbCursorBase *csr, bool remove_from_txncsrs = true);
+
+}; // ResourceManager
+
+END_NS
+#ifdef WIN32
+#pragma warning( pop )
+#endif
+#endif // !_DB_STL_RESOURCE_MANAGER_H__
diff --git a/stl/dbstl_set.h b/stl/dbstl_set.h
new file mode 100644
index 0000000..1aaf9f2
--- /dev/null
+++ b/stl/dbstl_set.h
@@ -0,0 +1,1583 @@
+/*-
+ * See the file LICENSE for redistribution information.
+ *
+ * Copyright (c) 2009 Oracle.  All rights reserved.
+ *
+ * $Id$
+ */
+
+#ifndef _DB_STL_DB_SET_H_
+#define _DB_STL_DB_SET_H_
+
+
+#include "dbstl_common.h"
+#include "dbstl_map.h"
+#include "dbstl_dbc.h"
+#include "dbstl_container.h"
+#include "dbstl_resource_manager.h"
+#include "dbstl_element_ref.h"
+#include "dbstl_base_iterator.h"
+
+START_NS(dbstl)
+
+using std::pair;
+using std::make_pair;
+
+/////////////////////////////////////////////////////////////////////////
+/////////////////////////////////////////////////////////////////////////
+//
+// _DB_STL_set_value class template definition
+// This class is used for db_set as value type because it inherits from
+// db_map . It dose not need a byte for DB_HASH to work, hash db can store
+// duplicated keys with empty data.
+//
+template <Typename T>
+class _DB_STL_set_value 
+{
+public:
+	
+	inline _DB_STL_set_value(const ElementRef<T>&){ }
+	inline _DB_STL_set_value(const T&){}
+	inline _DB_STL_set_value(){}
+};
+
+/** \ingroup dbstl_iterators
+@{
+\defgroup dbset_iterators Iterator classes for db_set and db_multiset.
+db_set_base_iterator and db_set_iterator are the const iterator and iterator 
+class for db_set and db_multiset. They have identical behaviors to 
+std::set::const_iterator and std::set::iterator respectively. 
+
+The difference between the two classes is that the db_set_base_iterator 
+can only be used to read its referenced value, while db_set_iterator allows
+both read and write access. If the access pattern is readonly, it is strongly
+recommended that you use the const iterator because it is faster and more 
+efficient.
+
+The two classes inherit several functions from db_map_base_iterator and 
+db_map_iterator respectively.
+\sa db_map_base_iterator db_map_iterator
+
+@{
+*/
+
+/////////////////////////////////////////////////////////////////////////
+/////////////////////////////////////////////////////////////////////////
+//
+// db_set_base_iterator class template definition
+//
+// db_set_base_iterator class template is the const iterator class for db_set
+// and db_multiset, it can only be used to read data.
+// This class need to override operator* and operator-> because the 
+// db_set<>::value_type is different from db_map<>::value_type. We also has
+// to copy the iterator movement operators into this class because the "self"
+// type is different in db_map_base_iterator and this class.
+// In db_set_base_iterator's inherited curpair_base_ pair, we store key to
+// its first and second member, to work with db_map and db_multimap.
+// Besides this, there is no further difference, so we can still safely make
+// use of its inherited methods.
+//
+template <Typename kdt>
+class _exported db_set_base_iterator : public 
+    db_map_base_iterator<kdt, kdt, _DB_STL_set_value<kdt> >
+{
+protected:
+	typedef db_set_base_iterator<kdt> self;
+	typedef db_map_base_iterator<kdt, kdt, _DB_STL_set_value<kdt> > base;
+	using db_base_iterator<kdt>::replace_current_key;
+public:
+	
+	typedef kdt key_type;
+	typedef _DB_STL_set_value<kdt> ddt;
+	typedef kdt value_type;
+	typedef value_type& reference;
+	typedef value_type* pointer;
+	typedef value_type value_type_wrap;
+	typedef ptrdiff_t difference_type;
+	typedef difference_type distance_type;
+	// We have to use std iterator tags to match the parameter list of
+	// stl internal functions, so we don't need to write our own tag 
+	// classes
+	//
+	typedef std::bidirectional_iterator_tag iterator_category;
+
+	////////////////////////////////////////////////////////////////
+	// Begin constructors and destructor definitions.
+	//
+	/// \name Constructors and destructor
+	/// Do not use these constructors to create iterators, but call
+	/// db_set::begin() const or db_multiset::begin() const to create 
+	/// valid iterators.
+	//@{
+	/// Destructor.
+	virtual ~db_set_base_iterator()
+	{
+
+	}
+
+	/// Constructor.
+	/// \param powner The container which creates this iterator.
+	/// \param b_bulk_retrieval The bulk read buffer size. 0 means 
+	/// bulk read disabled.
+	/// \param brmw Whether set DB_RMW flag in underlying cursor.
+	/// \param directdbget Whether do direct database get rather than
+	/// using key/data values cached in the iterator whenever read.
+	/// \param b_read_only Whether open a read only cursor. Only effective
+	/// when using Berkeley DB Concurrent Data Store.
+	explicit db_set_base_iterator(db_container*powner, 
+	    u_int32_t b_bulk_retrieval = 0, bool brmw = false, 
+	    bool directdbget = true, bool b_read_only = false)
+	    : base(powner, b_bulk_retrieval, brmw, directdbget, b_read_only)
+	{
+		this->is_set_ = true;
+	}
+
+	/// Default constructor, dose not create the cursor for now.
+	db_set_base_iterator() : base()
+	{
+		this->is_set_ = true;
+	}
+
+	/// Copy constructor.
+	/// \param s The other iterator of the same type to initialize this.
+	db_set_base_iterator(const db_set_base_iterator&s) : base(s)
+	{
+		this->is_set_ = true;
+	}
+
+	/// Base copy constructor.
+	/// \param bo Initialize from a base class iterator.
+	db_set_base_iterator(const base& bo) : base(bo) 
+	{
+		this->is_set_ = true;
+	}
+	//@}
+	////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////
+	// Begin functions that shift iterator positions.
+	/// \name Iterator movement operators.
+	/// These functions are identical to those of db_map_base_iterator
+	/// and db_map_iterator and db_set_iterator. Actually the iterator
+	/// movement functions in the four classes are the same.
+	//@{
+	// But we have to copy them into the four classes because the 
+	// return type, namely "self" is different in each class.
+	/// Post-increment. 
+	/// \return This iterator after incremented.
+	/// \sa db_map_base_iterator::operator++()
+	inline self& operator++()
+	{
+		this->next();
+		
+		return *this;
+	}
+
+	/// Pre-increment. 
+	/// \return Another iterator having the old value of this iterator.
+	/// \sa db_map_base_iterator::operator++(int)
+	inline self operator++(int)
+	{
+		self itr = *this;
+
+		this->next();
+		
+		return itr;
+	}
+
+	/// Post-decrement. 
+	/// \return This iterator after decremented.
+	/// \sa db_map_base_iterator::operator--()
+	inline self& operator--() 
+	{
+		this->prev();
+		
+		return *this;
+	}
+
+	/// Pre-decrement. 
+	/// \return Another iterator having the old value of this iterator.
+	/// \sa db_map_base_iterator::operator--(int)
+	self operator--(int)
+	{
+		self itr = *this;
+		this->prev();
+		
+		return itr;
+	}
+	//@}
+	////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////
+	// Begin functions that retrieve values from iterator.
+	//
+	// This function returns a read only reference, you can only read
+	// its referenced data, not update it.
+	// curpair_base_ is always kept updated on iterator movement, but it
+	// is also updated here before making use of the value it points
+	// to, which is stored in curpair_base_ .
+	// Even if this iterator is invalid, this call is allowed, the
+	// default value of type T is returned.
+	//
+	/// \name Functions that retrieve values from iterator.
+	//@{
+	/// Dereference operator.
+	/// Return the reference to the cached data element, which is an 
+	/// object of type T. You can only use the return value to read 
+	/// its referenced data element, can not update it.
+	/// \return Current data element reference object, i.e. ElementHolder
+	/// or ElementRef object.
+	inline reference operator*()  
+	{ 
+		int ret;
+
+		if (this->directdb_get_) {
+			ret = this->pcsr_->get_current_key(
+			    this->curpair_base_.first);
+			dbstl_assert(ret == 0);
+		// curpair_base_.second is a _DB_STL_set_value<kdt> object, 
+		// not used at all. Since const iterators can't be used to 
+		// write, so this is not a problem.
+		}
+		// Returning reference, no copy construction.
+		return this->curpair_base_.first;
+	}
+	 
+	// curpair_base_ is always kept updated on iterator movement, but it
+	// is also updated here before making use of the value it points
+	// to, which is stored in curpair_base_ .
+	// Even if this iterator is invalid, this call is allowed, the
+	// default value of type T is returned.
+	/// Arrow operator.
+	/// Return the pointer to the cached data element, which is an 
+	/// object of type T. You can only use the return value to read 
+	/// its referenced data element, can not update it.
+	/// \return Current data element reference object's address, i.e. 
+	/// address of ElementHolder or ElementRef object.
+	inline pointer operator->() const
+	{
+		int ret;
+
+		if (this->directdb_get_) {
+			ret = this->pcsr_->get_current_key(
+			    this->curpair_base_.first);
+			dbstl_assert(ret == 0);
+		}
+
+		return &(this->curpair_base_.first);
+	}
+	//@}
+	////////////////////////////////////////////////////////////////
+
+	/// \brief Refresh iterator cached value.
+	/// \param from_db If not doing direct database get and this parameter
+	/// is true, we will retrieve data directly from db.
+	/// \sa db_base_iterator::refresh(bool) 
+	virtual int refresh(bool from_db = true) const
+	{
+		
+		if (from_db && !this->directdb_get_)
+			this->pcsr_->update_current_key_data_from_db(
+			    DbCursorBase::SKIP_NONE);
+		this->pcsr_->get_current_key(this->curpair_base_.first);
+		this->curpair_base_.second = this->curpair_base_.first;
+		return 0;
+	}
+
+protected:
+
+	// Declare friend classes to access protected/private members,
+	// while expose to outside only methods in stl specifications.
+	//
+	friend class db_set<kdt>;
+	
+	friend class db_map<kdt, _DB_STL_set_value<kdt>, 
+	    ElementHolder<kdt>, self>;
+	friend class db_map<kdt, _DB_STL_set_value<kdt>, 
+	    ElementRef<kdt>, self>;
+
+	typedef pair<kdt, value_type> curpair_type;
+
+}; // db_set_base_iterator
+
+
+/////////////////////////////////////////////////////////////////////////
+/////////////////////////////////////////////////////////////////////////
+//
+// db_set_iterator class template definition
+//
+// db_set_iterator class template is the iterator class for db_set and 
+// db_multiset, it can be used to update its referenced key/data pair.
+// This class need to override operator* and operator-> because the 
+// db_set<>::value_type is different from db_map<>::value_type. besides
+// this, there is no further difference, so we can still safely make
+// use of db_set inherited methods.
+//
+template <Typename kdt, Typename value_type_sub>
+class _exported db_set_iterator : 
+    public db_map_iterator<kdt, _DB_STL_set_value<kdt>, value_type_sub>
+{
+protected:
+	typedef db_set_iterator<kdt, value_type_sub> self;
+	typedef db_map_iterator<kdt, _DB_STL_set_value<kdt>, 
+	    value_type_sub> base;
+	
+public:
+	
+	typedef kdt key_type;
+	typedef _DB_STL_set_value<kdt> ddt;
+	typedef kdt value_type;
+	typedef value_type_sub value_type_wrap;
+	typedef value_type_sub& reference;
+	typedef value_type_sub* pointer;
+	typedef ptrdiff_t difference_type;
+	typedef difference_type distance_type;
+	// We have to use std iterator tags to match the parameter list of
+	// stl internal functions, so we don't need to write our own tag 
+	// classes
+	//
+	typedef std::bidirectional_iterator_tag iterator_category;
+	
+	////////////////////////////////////////////////////////////////
+	// Begin constructors and destructor definitions.
+	/// \name Constructors and destructor
+	/// Do not use these constructors to create iterators, but call
+	/// db_set::begin() or db_multiset::begin() to create valid ones.
+	//@{
+	/// Destructor.
+	virtual ~db_set_iterator()
+	{
+
+	}
+
+	/// Constructor.
+	/// \param powner The container which creates this iterator.
+	/// \param b_bulk_retrieval The bulk read buffer size. 0 means 
+	/// bulk read disabled.
+	/// \param brmw Whether set DB_RMW flag in underlying cursor.
+	/// \param directdbget Whether do direct database get rather than
+	/// using key/data values cached in the iterator whenever read.
+	/// \param b_read_only Whether open a read only cursor. Only effective
+	/// when using Berkeley DB Concurrent Data Store.
+	explicit db_set_iterator(db_container*powner, 
+	    u_int32_t b_bulk_retrieval = 0, bool brmw = false, 
+	    bool directdbget = true, bool b_read_only = false)
+	    : base(powner, b_bulk_retrieval, brmw, directdbget, b_read_only)
+	{
+		this->is_set_ = true;
+	}
+
+	/// Default constructor, dose not create the cursor for now.
+	db_set_iterator() : base()
+	{
+		this->is_set_ = true;
+	}
+
+	/// Copy constructor.
+	/// \param s The other iterator of the same type to initialize this.
+	db_set_iterator(const db_set_iterator&s) : base(s)
+	{
+		this->is_set_ = true;
+	}
+
+	/// Base copy constructor.
+	/// \param bo Initialize from a base class iterator.
+	db_set_iterator(const base& bo) : base(bo) 
+	{
+		this->is_set_ = true;
+	}
+
+	/// Sibling copy constructor.
+	/// Note that this class does not derive from db_set_base_iterator
+	/// but from db_map_iterator.
+	/// \param bs Initialize from a base class iterator.
+	db_set_iterator(const db_set_base_iterator<kdt>&bs) : base(bs)
+	{
+		this->is_set_ = true;
+	}
+	//@}
+	////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////
+	// Begin functions that shift iterator positions.
+	/// \name Iterator movement operators.
+	//@{
+	/// Pre-increment.
+	/// Identical to those of db_map_iterator.
+	/// \return This iterator after incremented.
+	/// \sa db_map_iterator::operator++()
+	inline self& operator++()
+	{
+		this->next();
+		
+		return *this;
+	}
+
+	/// Post-increment.
+	/// \return Another iterator having the old value of this iterator.
+	/// \sa db_map_iterator::operator++(int)
+	inline self operator++(int)
+	{
+		self itr = *this;
+
+		this->next();
+		
+		return itr;
+	}
+
+	/// Pre-decrement.
+	/// \return This iterator after decremented.
+	/// \sa db_map_iterator::operator--()
+	inline 	self& operator--() 
+	{
+		this->prev();
+		
+		return *this;
+	}
+
+	/// Post-decrement 
+	/// \return Another iterator having the old value of this iterator.
+	/// \sa db_map_iterator::operator--(int)
+	self operator--(int)
+	{
+		self itr = *this;
+		this->prev();
+		
+		return itr;
+	}
+	//@}
+	////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////
+	// Begin functions that retrieve values from iterator.
+	//
+	// This functions returns a read-write reference to its data element.
+	// Even if this iterator is invalid, this call is allowed, the
+	// default value of type T is returned.
+	/// \name Functions that retrieve values from iterator.
+	//@{
+	/// Dereference operator.
+	/// Return the reference to the cached data element, which is an 
+	/// ElementRef<T> object if T is a class type or an ElementHolder<T>
+	/// object if T is a C++ primitive data type.
+	/// \return Current data element reference object, i.e. ElementHolder
+	/// or ElementRef object.
+	inline reference operator*()  
+	{ 
+
+		if (this->directdb_get_) 
+			refresh(true);
+		// returning reference, no copy construction
+		return this->curpair_.second;
+	}
+	 
+	// curpair_ is always kept updated on iterator movement, but it
+	// is also updated here before making use of the value it points
+	// to, which is stored in curpair_ .
+	// Even if this iterator is invalid, this call is allowed, the
+	// default value of type T is returned.
+	/// Arrow operator.
+	/// Return the pointer to the cached data element, which is an 
+	/// ElementRef<T> object if T is a class type or an ElementHolder<T>
+	/// object if T is a C++ primitive data type.
+	/// \return Current data element reference object's address, i.e. 
+	/// address of ElementHolder or ElementRef object.
+	inline pointer operator->() const
+	{
+
+		if (this->directdb_get_) 
+			refresh(true);
+
+		return &(this->curpair_.second);
+	}
+	//@}
+	////////////////////////////////////////////////////////////////
+
+	/// \brief Refresh iterator cached value.
+	/// \param from_db If not doing direct database get and this parameter
+	/// is true, we will retrieve data directly from db.
+	/// \sa db_base_iterator::refresh(bool) 
+	virtual int refresh(bool from_db = true) const
+	{
+		
+		if (from_db && !this->directdb_get_)
+			this->pcsr_->update_current_key_data_from_db(
+			    DbCursorBase::SKIP_NONE);
+		this->pcsr_->get_current_key(this->curpair_.first);
+		this->curpair_.second._DB_STL_CopyData(this->curpair_.first);
+		this->set_curpair_base(this->curpair_.first, this->curpair_.first);
+		return 0;
+	}
+
+protected:
+	typedef pair<kdt, value_type_sub> curpair_type;
+	typedef db_set_base_iterator<kdt> const_version;
+	// Declare friend classes to access protected/private members,
+	// while expose to outside only methods in stl specifications.
+	//
+	friend class db_set<kdt, ElementHolder<kdt> >;
+	friend class db_set<kdt, ElementRef<kdt> >;
+	friend class db_multiset<kdt, ElementHolder<kdt> >;
+	friend class db_multiset<kdt, ElementRef<kdt> >;
+	friend class db_map<kdt, _DB_STL_set_value<kdt>, 
+	    ElementHolder<kdt>, self>;
+	friend class db_multimap<kdt, _DB_STL_set_value<kdt>, 
+	    ElementHolder<kdt>, self>;
+	friend class db_map<kdt, _DB_STL_set_value<kdt>, 
+	    ElementRef<kdt>, self>;
+	friend class db_multimap<kdt, _DB_STL_set_value<kdt>, 
+	    ElementRef<kdt>, self>;
+	
+	virtual void delete_me() const
+	{
+		delete this;
+	}
+
+}; // db_set_iterator
+//@} // dbset_iterators
+//@} // dbstl_iterators
+
+/////////////////////////////////////////////////////////////////////////
+/////////////////////////////////////////////////////////////////////////
+//
+// db_set class template definition
+//
+// db_set<> inherits from db_map<>, storing nothing data, because
+// we only need the key. It uses db_set_iterator<>/db_set_base_iterator
+// as its iterator and const iterator respectively.
+// The only difference between db_set<> and db_map<> classes
+// is the value_type, so we redefine the insert function by directly copying
+// the db_map<>::insert, in order to make use of the newly defined 
+// value_type of db_set. If typedef could be dynamically bound, we won't
+// have to make this duplicated effort.
+/// \ingroup dbstl_containers
+/// This class is the combination of std::set and hash_set. By setting 
+/// database handles of DB_BTREE or DB_HASH type, you will be using the 
+/// equivalent of std::set or hash_set. This container stores the key in the
+/// key element of a key/data pair in the underlying database, 
+/// but doesn't store anything in the data element.
+/// Database and environment handle requirement:
+/// The same as that of db_map.
+/// \param kdt The key data type.
+/// \param value_type_sub If kdt is a class/struct type, do not specify 
+/// anything in this parameter; Otherwise specify ElementHolder<kdt>.
+/// \sa db_map db_container
+//
+template <Typename kdt, Typename value_type_sub>
+class _exported db_set : public db_map<kdt, _DB_STL_set_value<kdt>, 
+    value_type_sub, db_set_iterator<kdt, value_type_sub> > 
+{
+protected:
+	typedef db_set<kdt, value_type_sub> self;
+public:
+	typedef db_set_iterator<kdt, value_type_sub> iterator;
+	typedef typename iterator::const_version const_iterator;
+	typedef db_reverse_iterator<iterator, const_iterator> reverse_iterator;
+	typedef db_reverse_iterator<const_iterator, iterator> 
+		const_reverse_iterator;
+	typedef kdt key_type;
+	typedef ptrdiff_t difference_type;
+	// the ElementRef should store key value because key is also data, 
+	// and *itr is key and data value
+	//
+	typedef kdt value_type; 
+	typedef value_type_sub value_type_wrap;
+	typedef value_type_sub* pointer;
+	typedef value_type_sub& reference;
+	typedef value_type& const_reference;
+	typedef size_t size_type;
+
+	////////////////////////////////////////////////////////////////
+	// Begin constructors and destructor.
+	/// \name Constructors and destructor
+	//@{
+	/// Create a std::set/hash_set equivalent associative container.
+	/// See the handle requirement in class details to pass correct 
+	/// database/environment handles.
+	/// \param dbp The database handle.
+	/// \param envp The database environment handle.
+	/// \sa db_map(Db*, DbEnv*) db_container(Db*, DbEnv*)
+	explicit db_set (Db *dbp = NULL, DbEnv* envp = NULL) : base(dbp, envp){
+		// There are some special handling in db_map_iterator<> 
+		// if owner is set.
+		this->set_is_set(true);
+	}
+
+	/// Iteration constructor. Iterates between first and last, 
+	/// copying each of the elements in the range into 
+	/// this container. 
+	/// Create a std::set/hash_set equivalent associative container.
+	/// Insert a range of elements into the database. The range is
+	/// [first, last), which contains elements that can
+	/// be converted to type ddt automatically.
+	/// This function supports auto-commit.
+	/// See the handle requirement in class details to pass correct
+	/// database/environment handles.
+	/// \param dbp The database handle.
+	/// \param envp The database environment handle.
+	/// \param first The closed boundary of the range.
+	/// \param last The open boundary of the range.
+	/// \sa db_map(Db*, DbEnv*, InputIterator, InputIterator)
+	template <class InputIterator> 
+	db_set (Db *dbp, DbEnv* envp, InputIterator first,
+	    InputIterator last) : base(*(new BulkRetrievalOption(
+	    BulkRetrievalOption::BulkRetrieval)))
+	{
+
+		const char *errmsg;
+		
+		this->init_members(dbp, envp);
+		this->open_db_handles(dbp, envp, DB_BTREE, 
+		    DB_CREATE | DB_THREAD, 0);
+		if ((errmsg = this->verify_config(dbp, envp)) != NULL) {
+			THROW(InvalidArgumentException, ("Db*", errmsg));
+		}
+		this->set_db_handle_int(dbp, envp);
+		this->set_auto_commit(dbp);
+		this->begin_txn();
+		try {
+			insert(first, last);
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+		this->commit_txn();
+		// There are some special handling in db_map_iterator<> 
+		// if owner is set.
+		this->set_is_set(true);
+
+	}
+
+	/// Copy constructor.
+	/// Create a database and insert all key/data pairs in x into this
+	/// container. x's data members are not copied.
+	/// This function supports auto-commit.
+	/// \param x The source container to initialize this container.
+	/// \sa db_map(const db_map&) db_container(const db_container&)
+	db_set(const self& x) : base(*(new BulkRetrievalOption(
+	    BulkRetrievalOption::BulkRetrieval))) 
+	{
+		this->init_members(x);
+		verify_db_handles(x);
+		this->set_db_handle_int(this->clone_db_config(
+		    x.get_db_handle()), x.get_db_env_handle());
+		assert(this->get_db_handle() != NULL);
+		
+		this->begin_txn();
+		try {
+			copy_db((self&)x);
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+		this->commit_txn();
+		// There are some special handling in db_map_iterator<> 
+		// if owner is set.
+		this->set_is_set(true);
+	}
+
+	virtual ~db_set(){}
+	//@}
+	////////////////////////////////////////////////////////////////
+
+	/// Container content assignment operator.
+	/// This function supports auto-commit.
+	/// \param x The source container whose key/data pairs will be 
+	/// inserted into the target container. Old content in the target
+	/// container is discarded.
+	/// \return The container x's reference.
+	/// \sa http://www.cplusplus.com/reference/stl/set/operator=/
+	const self& operator=(const self& x)
+	{
+		ASSIGNMENT_PREDCOND(x)
+		db_container::operator =(x);
+		verify_db_handles(x);
+		assert(this->get_db_handle() != NULL);
+		this->begin_txn();
+		try {
+			this->copy_db((self &)x);
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+		this->commit_txn();
+		return x;
+	}
+	
+	////////////////////////////////////////////////////////////////
+	// Begin key/value compare classes/functions.
+	//
+	// key_compare class definition, it is defined as an inner class,
+	// using underlying btree/hash db's compare function. It is the same
+	// as that of db_map<>, but because we have to redefine value_compare
+	// in this class, gcc forces us to also define key_compare again.
+	class key_compare 
+	{
+	private:
+		Db*pdb;
+	public:
+		key_compare(Db*pdb1)
+		{
+			pdb = pdb1;
+		}
+		bool operator()(const kdt& k1, const kdt& k2) const
+		{
+			return compare_keys(pdb, k1, k2);
+		}
+
+	}; // key_compare class definition
+	
+	class value_compare 
+	{
+		key_compare kc;
+	public:
+		value_compare(Db*pdb) : kc(pdb)
+		{
+		
+		}
+
+		bool operator()(const value_type& v1, 
+		    const value_type& v2) const
+		{
+			
+			return kc(v1, v2);
+		}
+
+	}; // value_compare class definition
+
+	/// Get value comparison functor.
+	/// \return The value comparison functor.
+	/// \sa http://www.cplusplus.com/reference/stl/set/value_comp/
+	inline value_compare value_comp() const
+	{
+		return value_compare(this->get_db_handle());
+	}
+	////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////
+	// Begin insert functions and swap function.
+	//
+	// Note that when secondary index is enabled, each db_container
+	// can create a db_multimap secondary container, but the insert 
+	// function is not functional.
+	//
+	// Insert functions. Note that stl requires if the entry with x.key 
+	// already exists, insert should not overwrite that entry and the 
+	// insert should fail; but bdb Dbc::cursor(DB_KEYLAST) will replace
+	// existing data with new one, so we will first find whether we
+	// have this data, if have, return false;
+	/// \name Insert Functions
+	/// \sa http://www.cplusplus.com/reference/stl/set/insert/
+	//@{
+	/// Insert a single key/data pair if the key is not in the container.
+	/// \param x The key/data pair to insert.
+	/// \return A pair P, if insert OK, i.e. the inserted key wasn't in the
+	/// container, P.first will be the iterator positioned on the inserted
+	/// key/data pair, and P.second is true; otherwise P.first is an invalid 
+	/// iterator equal to that returned by end() and P.second is false.
+	pair<iterator,bool> insert (const value_type& x ) 
+	{
+		pair<iterator,bool> ib;
+
+		_DB_STL_set_value<kdt> sv;
+		iterator witr;
+
+		this->init_itr(witr);
+		this->open_itr(witr);
+
+		if (witr.move_to(x) == 0) {// has it
+			ib.first = witr;
+			ib.second = false;
+
+			return ib;
+		}
+		witr.itr_status_ = witr.pcsr_->insert(x, sv, DB_KEYLAST); 
+		witr.refresh(false);
+		ib.first = witr;
+		ib.second = true;
+
+		return ib;
+	}
+
+	// NOT_AUTOCOMMIT_TAG  
+	// Note that if first and last are on same db as this container, 
+	// then insert may deadlock if there is no common transaction context 
+	// for first and witr (when they are on the same page).
+	// The insert function in base class can not be directly used, 
+	// got compile errors.
+	/// Range insertion. Insert a range [first, last) of key/data pairs
+	/// into this container.
+	/// \param first The closed boundary of the range.
+	/// \param last The open boundary of the range.
+	inline void insert (const_iterator& first, const_iterator& last) 
+	{
+		const_iterator ii;
+		_DB_STL_set_value<kdt> v;
+		iterator witr;
+
+		this->init_itr(witr);
+		
+		this->open_itr(witr);
+	
+		for (ii = first; ii != last; ++ii) 
+			witr.pcsr_->insert(*ii, v, DB_KEYLAST);
+	}
+
+	/// Range insertion. Insert a range [first, last) of key/data pairs
+	/// into this container.
+	/// \param first The closed boundary of the range.
+	/// \param last The open boundary of the range.
+	void insert (iterator& first, iterator& last) 
+	{
+		iterator ii, witr;
+		_DB_STL_set_value<kdt> d;
+
+		init_itr(witr);
+		open_itr(witr);
+	
+		for (ii = first; ii != last; ++ii)
+			witr.pcsr_->insert(*ii, d, DB_KEYLAST);
+		
+	}
+
+	// Ignore the position parameter because bdb knows better
+	// where to insert.
+	/// Insert with hint position. We ignore the hint position because 
+	/// Berkeley DB knows better where to insert.
+	/// \param position The hint position.
+	/// \param x The key/data pair to insert.
+	/// \return The iterator positioned on the inserted key/data pair, 
+	/// or an invalid iterator if the key was already in the container.
+	inline iterator insert ( iterator position, const value_type& x ) 
+	{
+		pair<iterator,bool> ib = insert(x);
+		return ib.first;
+	}
+
+	/// Range insertion. Insert a range [first, last) of key/data pairs
+	/// into this container.
+	/// \param first The closed boundary of the range.
+	/// \param last The open boundary of the range.
+	template <class InputIterator>
+	void insert (InputIterator first, InputIterator last) 
+	{
+		InputIterator ii;
+		_DB_STL_set_value<kdt> v;
+		iterator witr;
+
+		this->init_itr(witr);
+	
+		this->open_itr(witr);
+	
+		for (ii = first; ii != last; ++ii) 
+			witr.pcsr_->insert(*ii, v, DB_KEYLAST);
+
+	}
+	//@}
+
+	/// Swap content with another container.
+	/// This function supports auto-commit.
+	/// \param mp The container to swap content with.
+	/// \param b_truncate See db_vector::swap's b_truncate parameter
+	/// for details.
+	/// \sa db_map::swap() db_vector::clear()
+	void swap (db_set<kdt, value_type_sub>& mp, bool b_truncate = true)
+	{	
+		Db *swapdb = NULL;
+		std::string dbfname(64, '\0');
+
+		verify_db_handles(mp);
+		this->begin_txn();
+		try {
+			swapdb = this->clone_db_config(this->get_db_handle(), 
+			    dbfname);
+			
+			db_set<kdt, value_type_sub> tmap(swapdb, 
+			    swapdb->get_env(), this->begin(), this->end());
+			typename db_set<kdt, value_type_sub>::
+			    iterator itr1, itr2;
+
+			this->clear(b_truncate);// Clear this db_map<> object.
+			itr1 = mp.begin();
+			itr2 = mp.end();
+			this->insert(itr1, itr2);
+			mp.clear(b_truncate);
+			itr1 = tmap.begin();
+			itr2 = tmap.end();
+			mp.insert(itr1, itr2);
+			// tmap has no opened cursor, so simply truncate.
+			tmap.clear();
+			
+			swapdb->close(0);
+			if (dbfname[0] != '\0') {
+				swapdb = new Db(NULL, DB_CXX_NO_EXCEPTIONS);
+				swapdb->remove(dbfname.c_str(), NULL, 0);
+				swapdb->close(0);
+				delete swapdb;
+			}
+			this->commit_txn();
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}	
+		
+	}
+	////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////
+	// Begin container comparison functions.
+	//
+	// Return true if contents in m1 and m2 are identical otherwise 
+	// return false. 
+	// 
+	// Note that we don't require the keys' order be identical, we are
+	// doing mathmatical set comparisons.
+	/// Set content equality comparison operator.
+	/// Return if the two containers have identical content. This function
+	/// does not rely on key order.
+	/// Two sets A and B are equal if and only if A contains B and B 
+	/// contains A.
+	/// \param m2 The container to compare against.
+	/// \return Returns true if the two containers are equal, 
+	/// false otherwise.
+	//
+	bool operator==(const db_set<kdt, value_type_sub>& m2) const
+	{
+		bool ret;
+		
+		COMPARE_CHECK(m2)
+		verify_db_handles(m2);
+		const db_set<kdt, value_type_sub>& m1 = *this;
+
+		try {
+			this->begin_txn();
+			if (m1.size() != m2.size())
+				ret = false;
+			else {
+				typename db_set<kdt, value_type_sub>::
+				    const_iterator i1;
+
+				for (i1 = m1.begin(); i1 != m1.end(); ++i1) {
+					if (m2.count(*i1) == 0) {
+						ret = false;
+						goto exit;
+					}
+						
+				} // for
+				ret = true;
+			} // else
+exit:
+			this->commit_txn();
+	// Now that m1 and m2 has the same number of unique elements and 
+	// all elements of m1 are in m2, thus there can be no element of m2 
+	// that dose not belong to m1, so we won't verify each element of 
+	// m2 are in m1.
+			return ret;
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+	}// operator==
+
+	/// Inequality comparison operator.
+	bool operator!=(const db_set<kdt, value_type_sub>& m2) const
+	{
+		return !this->operator==(m2);
+	}
+	////////////////////////////////////////////////////////////////
+	
+protected:
+	typedef int (*db_compare_fcn_t)(Db *db, const Dbt *dbt1, 
+	    const Dbt *dbt2);
+	
+	
+	typedef db_map<kdt, _DB_STL_set_value<kdt>, value_type_sub,
+	    db_set_iterator<kdt, value_type_sub> > base;
+private:
+
+	value_type_sub operator[] (const key_type& x)
+	{
+		THROW(NotSupportedException, ("db_set<>::operator[]"));
+		
+	}
+
+	value_type_sub operator[] (const key_type& x) const
+	{
+		THROW(NotSupportedException, ("db_set<>::operator[]"));
+		
+	}
+
+	inline void copy_db(db_set<kdt, value_type_sub> &x)
+	{	 
+
+		// Make sure clear can succeed if there are cursors 
+		// open in other threads.
+		this->clear(false);
+		insert(x.begin(), x.end());
+		
+	}
+
+}; // db_set<>
+
+
+/////////////////////////////////////////////////////////////////////////
+/////////////////////////////////////////////////////////////////////////
+//
+// db_multiset class template definition
+//
+// db_multiset<> inherits from db_multimap, storing nothing as data, because
+// we only need the key. It uses db_set_iterator<> and db_set_base_iterator<>
+// as its iterator and const iterator respectively, so that
+// we can safely make use of the inherited methods. The only difference
+// is the value_type, so we redefine the insert functions by directly copying
+// the db_map<>::insert versions, in order to make use of the newly defined 
+// value_type of db_multiset. If typedef could be dynamically bound, we won't
+// have to make this duplicated effort.
+/// \ingroup dbstl_containers
+/// This class is the combination of std::multiset and hash_multiset. By 
+/// setting database handles of DB_BTREE or DB_HASH type respectively, you 
+/// will be using the equivalent of std::multiset or hash_multiset respectively.
+/// This container stores the key in the key element of a key/data pair in 
+/// the underlying database, but doesn't store anything in the data element.
+/// Database and environment handle requirement:
+/// The requirement to these handles is the same as that to db_multimap.
+/// \param kdt The key data type.
+/// \param value_type_sub If kdt is a class/struct type, do not specify 
+/// anything in this parameter; Otherwise specify ElementHolder<kdt>.
+/// \sa db_multimap db_map db_container db_set
+//
+template <Typename kdt, Typename value_type_sub>
+class _exported db_multiset : public db_multimap<kdt, _DB_STL_set_value<kdt>, 
+    value_type_sub, db_set_iterator<kdt, value_type_sub> >
+{
+protected:
+	typedef db_multiset<kdt, value_type_sub> self;
+public:
+	typedef db_set_iterator<kdt, value_type_sub> iterator;
+	typedef typename iterator::const_version const_iterator;
+	typedef db_reverse_iterator<iterator, const_iterator> reverse_iterator;
+	typedef db_reverse_iterator<const_iterator, iterator> 
+		const_reverse_iterator;
+	typedef kdt key_type;
+	typedef ptrdiff_t difference_type;
+	// The ElementRef should store key value because key is also data, 
+	// and *itr is key and data value.
+	//
+	typedef kdt value_type; 
+	typedef value_type_sub value_type_wrap;
+	typedef value_type_sub& reference;
+	typedef const value_type& const_reference;
+	typedef value_type_sub* pointer;
+	typedef size_t size_type;
+
+public:
+	////////////////////////////////////////////////////////////////
+	// Begin constructors and destructor.
+	/// \name Constructors and destructor
+	//@{
+	/// Create a std::multiset/hash_multiset equivalent associative 
+	/// container.
+	/// See the handle requirement in class details to pass correct 
+	/// database/environment handles.
+	/// \param dbp The database handle.
+	/// \param envp The database environment handle.
+	/// \sa db_multimap(Db*, DbEnv*)
+	explicit db_multiset (Db *dbp = NULL, DbEnv* envp = NULL) : 
+	    base(dbp, envp) {
+		// There are special handling in db_map_iterator<> if owner 
+		// is a set.
+		this->set_is_set(true);
+	}
+
+	/// Iteration constructor. Iterates between first and last, 
+	/// copying each of the elements in the range into 
+	/// this container. 
+	/// Create a std::multi/hash_multiset equivalent associative container.
+	/// Insert a range of elements into the database. The range is
+	/// [first, last), which contains elements that can
+	/// be converted to type ddt automatically.
+	/// This function supports auto-commit.
+	/// See the handle requirement in class details to pass correct
+	/// database/environment handles.
+	/// \param dbp The database handle.
+	/// \param envp The database environment handle.
+	/// \param first The closed boundary of the range.
+	/// \param last The open boundary of the range.
+	/// \sa db_multimap(Db*, DbEnv*, InputIterator, InputIterator)
+	template <class InputIterator> 
+	db_multiset (Db *dbp, DbEnv* envp, InputIterator first, 
+	    InputIterator last) : base(*(new BulkRetrievalOption(
+	    BulkRetrievalOption::BulkRetrieval)))
+	{
+
+		const char *errmsg;
+
+		this->init_members(dbp, envp);
+		this->open_db_handles(dbp, envp, DB_BTREE, DB_CREATE | 
+		    DB_THREAD, DB_DUP);
+		// Note that we can't call base(dbp, envp) here because it 
+		// will verify failed; And we can't call db_container 
+		// directly because it is illegal to do so.
+		if ((errmsg = verify_config(dbp, envp)) != NULL) {
+			THROW(InvalidArgumentException, ("Db*", errmsg));
+			
+		}
+		this->set_db_handle_int(dbp, envp);
+		this->set_auto_commit(dbp);
+
+		this->begin_txn();
+		try {
+			insert(first, last);
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+		this->commit_txn();
+
+		// There are special handling in db_map_iterator<> if owner 
+		// is a set.
+		this->set_is_set(true);
+
+	}
+
+	/// Copy constructor.
+	/// Create a database and insert all key/data pairs in x into this
+	/// container. x's data members are not copied.
+	/// This function supports auto-commit.
+	/// \param x The source container to initialize this container.
+	/// \sa db_multimap(const db_multimap&) db_container(const db_container&)
+	db_multiset(const self& x) : base(*(new BulkRetrievalOption(
+	    BulkRetrievalOption::BulkRetrieval))) 
+	{
+		this->init_members(x);
+		verify_db_handles(x);
+		this->set_db_handle_int(this->clone_db_config(
+		    x.get_db_handle()), x.get_db_env_handle());
+		assert(this->get_db_handle() != NULL);
+
+		this->begin_txn();
+		try {
+			copy_db((self&)x);
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+		this->commit_txn();
+
+		// There are special handling in db_map_iterator<> if owner 
+		// is a set.
+		this->set_is_set(true);
+	}
+
+	virtual ~db_multiset(){}
+	//@}
+	////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////
+	// Begin functions that modify the container's content, i.e. insert,
+	// erase, assignment and swap functions.
+	//
+	/// Container content assignment operator.
+	/// This function supports auto-commit.
+	/// \param x The source container whose key/data pairs will be 
+	/// inserted into the target container. Old content in the target 
+	/// container is discarded.
+	/// \return The container x's reference.
+	/// \sa http://www.cplusplus.com/reference/stl/multiset/operator=/
+	inline const self& operator=(const self& x)
+	{
+		ASSIGNMENT_PREDCOND(x)
+		db_container::operator =(x);
+		verify_db_handles(x);
+		assert(this->get_db_handle() != NULL);
+		this->begin_txn();
+		try {
+			this->copy_db((self &)x);
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+		this->commit_txn();
+		return x;
+	}
+
+	// Note that when secondary index is enabled, each db_container
+	// can create a db_multimap secondary container, but the insert 
+	// function is not functional.
+	/// \name Insert Functions
+	/// \sa http://www.cplusplus.com/reference/stl/multiset/insert/
+	//@{
+	/// Insert a single key if the key is not in the container.
+	/// \param x The key to insert.
+	/// \return An iterator positioned on the newly inserted key. If the
+	/// key x already exists, an invalid iterator equal to that returned 
+	/// by end() function is returned.
+	inline iterator insert(const value_type& x ) 
+	{
+		pair<iterator,bool> ib;
+		_DB_STL_set_value<kdt> sv;
+		iterator witr;
+
+		this->init_itr(witr);
+		this->open_itr(witr);
+
+		witr.itr_status_ = witr.pcsr_->insert(x, sv, DB_KEYLAST);
+		witr.refresh(false);
+		return witr;
+	}
+
+	// Ignore the position parameter because bdb knows better
+	// where to insert.
+	/// Insert a single key with hint if the key is not in the container.
+	/// The hint position is ignored because Berkeley DB controls where
+	/// to insert the key.
+	/// \param x The key to insert.
+	/// \param position The hint insert position, ignored.
+	/// \return An iterator positioned on the newly inserted key. If the
+	/// key x already exists, an invalid iterator equal to that returned 
+	/// by end() function is returned.
+	inline iterator insert ( iterator position, const value_type& x ) 
+	{
+		return insert(x);
+	}
+	
+	/// Range insertion. Insert a range [first, last) of key/data pairs
+	/// into this container.
+	/// \param first The closed boundary of the range.
+	/// \param last The open boundary of the range.
+	template <class InputIterator>
+	void insert (InputIterator first, InputIterator last) 
+	{
+		InputIterator ii;
+		_DB_STL_set_value<kdt> v;
+
+		iterator witr;
+
+		this->init_itr(witr);	
+		this->open_itr(witr);
+		for (ii = first; ii != last; ++ii) 
+			witr.pcsr_->insert(*ii, v, DB_KEYLAST);
+
+	}
+
+	// Member function template overload.
+	// This function is a specialization for the member template version
+	// dedicated to db_set<>.
+	//
+	/// Range insertion. Insert a range [first, last) of key/data pairs
+	/// into this container.
+	/// \param first The closed boundary of the range.
+	/// \param last The open boundary of the range.
+	void insert (db_set_iterator<kdt, value_type_sub>& first, 
+	    db_set_iterator<kdt, value_type_sub>& last) 
+	{
+		db_set_iterator<kdt, value_type_sub> ii;
+		iterator witr;
+		_DB_STL_set_value<kdt> d;
+
+		init_itr(witr);
+		open_itr(witr);
+	
+		for (ii = first; ii != last; ++ii)
+			witr.pcsr_->insert(*ii, d, DB_KEYLAST);
+		
+
+	}
+
+	// Member function template overload.
+	// This function is a specialization for the member template version
+	// dedicated to db_set<>.
+	//
+	/// Range insertion. Insert a range [first, last) of key/data pairs
+	/// into this container.
+	/// \param first The closed boundary of the range.
+	/// \param last The open boundary of the range.
+	void insert (db_set_base_iterator<kdt>& first, 
+	    db_set_base_iterator<kdt>& last) 
+	{
+		db_set_base_iterator<kdt> ii;
+		iterator witr;
+		_DB_STL_set_value<kdt> d;
+
+		init_itr(witr);
+		open_itr(witr);
+	
+		for (ii = first; ii != last; ++ii)
+			witr.pcsr_->insert(*ii, d, DB_KEYLAST);
+	}
+	//@}
+
+	// There is identical function in db_multimap<> and db_multiset
+	// for this function, we MUST keep the code consistent on update!
+	// Go to db_multimap<>::erase(const key_type&) to see why.
+	/// \name Erase Functions
+	/// \sa http://www.cplusplus.com/reference/stl/multiset/erase/
+	//@{
+	/// Erase elements by key.
+	/// All key/data pairs with specified key x will be removed from 
+	/// the underlying database.
+	/// This function supports auto-commit.
+	/// \param x The key to remove from the container.
+	/// \return The number of key/data pairs removed.
+	size_type erase (const key_type& x) 
+	{
+		size_type cnt;
+		iterator itr;
+
+		this->begin_txn();
+		try {
+			pair<iterator, iterator> rg = equal_range(x);
+			for (itr = rg.first, cnt = 0; 
+			    itr != rg.second; ++itr) {
+				cnt++;
+				itr.pcsr_->del();
+			}
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+		this->commit_txn();
+		return cnt;
+	}
+
+	// Can not reopen external/outside iterator's cursor, pos must
+	// already have been in a transactional context.
+	// There is identical function in db_multimap<> and db_multiset
+	// for this function, we MUST keep the code consistent on update!
+	// Go to db_multimap<>::erase(const key_type&) to see why.
+	//
+	/// Erase a key/data pair at specified position.
+	/// \param pos A valid iterator of this container to erase.
+	inline void erase (iterator pos) 
+	{
+		if (pos == this->end())
+			return;
+		pos.pcsr_->del();
+	}
+
+	// Can not be auto commit because first and last are already open.
+	// There is identical function in db_multimap<> and db_multiset
+	// for this function, we MUST keep the code consistent on update!
+	// Go to db_multimap<>::erase(const key_type&) to see why.
+	//
+	/// Range erase. Erase all key/data pairs within the valid range 
+	/// [first, last).
+	/// \param first The closed boundary of the range.
+	/// \param last The open boundary of the range.
+	inline void erase (iterator first, iterator last) 
+	{
+		iterator i;
+
+		for (i = first; i != last; ++i)
+			i.pcsr_->del();
+	}
+	//@}
+
+	/// Swap content with another container.
+	/// This function supports auto-commit.
+	/// \param mp The container to swap content with.
+	/// \param b_truncate See db_multimap::swap() for details.
+	/// \sa db_map::swap() db_vector::clear()
+	void swap (db_multiset<kdt, value_type_sub>& mp, bool b_truncate = true)
+	{	
+		Db *swapdb = NULL;
+		std::string dbfname(64, '\0');
+
+		verify_db_handles(mp);
+		this->begin_txn();
+		try {
+			swapdb = this->clone_db_config(this->get_db_handle(), 
+			    dbfname);
+			
+			db_multiset<kdt, value_type_sub> tmap(swapdb, 
+			    swapdb->get_env(), this->begin(), this->end());
+			this->clear(b_truncate);// Clear this db_map<> object.
+			typename db_multiset<kdt, value_type_sub>::
+			    iterator itr1, itr2;
+			itr1 = mp.begin();
+			itr2 = mp.end();
+			this->insert(itr1, itr2);
+			mp.clear(b_truncate);
+			itr1 = tmap.begin();
+			itr2 = tmap.end();
+			mp.insert(itr1, itr2);
+			
+			tmap.clear();
+			
+			swapdb->close(0);
+			if (dbfname[0] != '\0') {
+				swapdb = new Db(NULL, DB_CXX_NO_EXCEPTIONS);
+				swapdb->remove(dbfname.c_str(), NULL, 0);
+				swapdb->close(0);
+				delete swapdb;
+			}
+			this->commit_txn();
+			
+		} catch (...) {
+			swapdb->close(0);
+			this->abort_txn();
+			throw;
+		}	
+		
+	}
+	////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////
+	// Begin container comparison functions.
+	//
+	// Compare two db_multiset containers for equality, containers
+	// containing identical set of keys are considered equal, keys'
+	// order are not presumed or relied upon by this comparison.
+	/// Container content equality compare operator.
+	/// This function does not rely on key order.
+	/// Two sets A and B are equal if and only if
+	/// for each and every key K having n occurrences in A, K has n 
+	/// occurrences in B, and for each and every key K` having N
+	/// occurrences in B, K` has n occurrences in A.
+	/// \param m2 The container to compare against.
+	/// \return Returns true if the two containers are equal, 
+	/// false otherwise.
+	bool operator==(const self& m2) const
+	{
+		COMPARE_CHECK(m2)
+		verify_db_handles(m2);
+
+		const db_multiset<kdt, value_type_sub> &m1 = *this;
+		const_iterator i1, i11;
+		pair<const_iterator, const_iterator> resrg1, resrg2;
+		size_t n1, n2;
+		bool ret = false;
+
+		try {
+			this->begin_txn();
+			if (m1.size() != m2.size())
+				ret = false;
+			else {
+				for (i1 = m1.begin(); i1 != m1.end(); ) {
+					resrg1 = m1.equal_range_N(*i1, n1);
+					resrg2 = m2.equal_range_N(*i1, n2);
+					if (n1 != n2) {
+						ret = false;
+						goto exit;
+					}
+						
+			// If both is 1, resrg2 may contain no i1->first.
+					if (n2 == 1 && !(*(resrg2.first) == 
+					    *(resrg1.first))) {
+						ret = false;
+						goto exit;
+					}
+			// m1 and m2 contains identical set of i1->first key,
+			// so move on, skip all equal keys in the range.
+			//
+					i1 = resrg1.second; 
+						
+				} // for
+				ret = true;
+
+			}// else
+exit:
+			this->commit_txn();
+			return ret;
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+
+	// Now that m1 and m2 has the same number of unique elements and all 
+	// elements of m1 are in m2, thus there can be no element of m2 that 
+	// dose not belong to m1, so we won't verify each element of m2 are 
+	// in m1.
+
+	} // operator==
+
+	/// Inequality comparison operator.	
+	bool operator!=(const self& m2) const
+	{
+		return !this->operator==(m2);
+	}
+	////////////////////////////////////////////////////////////////
+
+protected:
+	
+	typedef int (*db_compare_fcn_t)(Db *db, const Dbt *dbt1, 
+	    const Dbt *dbt2);
+	typedef db_multimap<kdt, _DB_STL_set_value<kdt>, 
+	    value_type_sub, db_set_iterator<kdt, value_type_sub> > base;
+
+	// Declare base our friend, we can't use 'friend class base' to do
+	// this declaration on gcc.
+	friend class db_multimap<kdt, _DB_STL_set_value<kdt>, 
+	    value_type_sub, db_set_iterator<kdt, value_type_sub> >; 
+	// Declare iterator our friend, we can't use 'friend class iterator'
+	// to do this declaration on gcc.
+	friend class db_set_iterator<kdt, value_type_sub>; 
+	friend class db_map_iterator<kdt, _DB_STL_set_value<kdt>, 
+	    value_type_sub>;
+	friend class db_map_iterator<kdt, _DB_STL_set_value<kdt> >;
+
+private:
+
+	inline void copy_db(db_multiset<kdt, value_type_sub> &x)
+	{	 
+
+		// Make sure clear can succeed if there are cursors 
+		// open in other threads.
+		this->clear(false);
+		insert(x.begin(), x.end());
+		
+	}
+
+	// Prevent user calling the inherited version.
+	value_type operator[] (const key_type& x)
+	{
+		THROW(NotSupportedException, ("db_multiset<>::operator[]"));
+		
+	}
+
+	value_type operator[] (const key_type& x) const
+	{
+		THROW(NotSupportedException, ("db_multiset<>::operator[]"));
+		
+	}
+
+	virtual const char* verify_config(Db*dbp, DbEnv* envp) const
+	{
+		DBTYPE dbtype;
+		u_int32_t oflags, sflags;
+		int ret;
+		const char *err = NULL;
+
+		err = db_container::verify_config(dbp, envp);
+		if (err)
+			return err;
+
+		BDBOP(dbp->get_type(&dbtype), ret);
+		BDBOP(dbp->get_open_flags(&oflags), ret);
+		BDBOP(dbp->get_flags(&sflags), ret);
+
+		if (dbtype != DB_BTREE && dbtype != DB_HASH)
+			err = 
+"wrong database type, only DB_BTREE and DB_HASH allowed for db_map<> class";
+		if (oflags & DB_TRUNCATE)
+			err = 
+"do not specify DB_TRUNCATE flag to create a db_map<> object";
+
+		// Must set DB_DUP and NOT DB_DUPSORT.
+		if (!(sflags & DB_DUP) || (sflags & DB_DUPSORT))
+			err = 
+"db_multiset<> requires a database with DB_DUP set and without DB_DUPSORT set.";
+		
+		if (sflags & DB_RECNUM)
+			err = "no DB_RECNUM flag allowed in db_map<>";
+		
+		return err;
+		
+	}
+
+}; // db_multiset<>
+
+
+END_NS
+
+#endif// !_DB_STL_DB_SET_H_
diff --git a/stl/dbstl_utility.h b/stl/dbstl_utility.h
new file mode 100644
index 0000000..8712341
--- /dev/null
+++ b/stl/dbstl_utility.h
@@ -0,0 +1,496 @@
+/*-
+ * See the file LICENSE for redistribution information.
+ *
+ * Copyright (c) 2009 Oracle.  All rights reserved.
+ *
+ * $Id$
+ */
+
+#ifndef _DB_STL_UTILITY_H__
+#define _DB_STL_UTILITY_H__
+
+#include "dbstl_inner_utility.h"
+
+START_NS(dbstl)
+
+// This class allows users to configure dynamically how a specific type of 
+// object is copied, stored, restored, and how to measure the type's
+// instance size.
+/** \defgroup dbstl_helper_classes dbstl helper classes
+Classes of this module help to achieve various features of dbstl.
+*/
+/** \ingroup dbstl_helper_classes
+@{
+This class is used to register callbacks to manipulate an object of a 
+complex type. These callbacks are used by dbstl at runtime  to 
+manipulate the object.
+
+A complex type is a type whose members are not located in a contiguous 
+chunk of memory. For example, the following class A is a complex type 
+because for any  instance a of class A, a.b_ points to another object 
+of type B, and dbstl treats the  object that a.b_ points to as part of 
+the data of the instance a. Hence, if the user needs to store a.b_ into 
+a dbstl container, the user needs to register an appropriate callback to 
+de-reference and store the object referenced by a.b. Similarly, the 
+user also needs to register callbacks to marshall an array as well as 
+to count the  number of elements in such an array.
+
+class A { int m; B *p_; };
+class B { int n; };
+
+The user also needs to register callbacks for  
+i). returning an object¡¯s size in bytes; 
+ii). Marshalling and unmarshalling an object;
+iii). Copying a complex object and  and assigning an object to another 
+object of the same type; 
+iv). Element comparison. 
+v). Compare two sequences of any type of objects; Measuring the length 
+of an object sequence and copy an object sequence.
+ 
+Several elements  located in a contiguous chunk of memory form a sequence. 
+An element of a sequence may be a simple object located at a contigous 
+memory chunk, or a complex object, i.e. some of its members may contain 
+references (pointers) to another region of memory. It is not necessary 
+to store a special object to denote the end of the sequence.  The callback 
+to traverse the constituent elements of the sequence needs to able to 
+determine the end of the sequence.
+
+Marshalling means packing the object's data members into a contiguous 
+chunk of memory; unmarshalling is the opposite of marshalling. In other 
+words, when you unmarshall an object, its data members are populated 
+with values from a previously marshalled version of the object.
+
+The callbacks need not be set to every type explicitly.  . dbstl will 
+check if a needed callback function of this type is provided. 
+If one is available, dbstl will use the registered callback.  If the 
+appropriate callback is not provided, dbstl will use reasonable defaults 
+to do the job.
+
+For returning the size of an object,  the default behavior is to use the 
+sizeof() operator;  For marshalling and unmarshalling, dbstl uses memcpy, 
+so the default behavior is  sufficient for simple types whose data reside 
+in a contiguous  chunk of memory; Dbstl uses  uses >, == and < for 
+comparison operations; For char* and wchar_t * strings, dbstl already 
+provides the appropriate callbacks, so you do not need to register them. 
+In general, if the default behavior is adequate, you don't need to 
+register the corresponding callback.
+
+If you have registered proper callbacks, the DbstlElemTraits<T> can also be
+used as the char_traits<T> class for std::basic_string<T, char_traits<T> >,
+and you can enable your class T to form a basic_string<T, DbstlElemTraits<T>>,
+and use basic_string's functionality and the algorithms to manipulate it.
+*/
+template <typename T>
+class _exported DbstlElemTraits : public DbstlGlobalInnerObject
+{
+public:
+	/// \name Callback_typedefs Function callback type definitions.
+	/// Following are the callback function types, there is one function
+	/// pointer data member for each of the type, and a pair of set/get
+	/// functions for each function callback data member, and this is 
+	/// the structure of this class.
+	//@{
+	/// Assign object src to object dest. Most often assignment callback 
+	/// is not needed - the class copy constructor is sufficient.
+	/// This description talks about the function of this type, rather 
+	/// than the type itself, this is true to all the types in the group.
+	typedef void (*ElemAssignFunct)(T& dest, const T&src);
+	/// Read data from the chunk of memory pointed by srcdata, and assign
+	/// to the object dest. This is also called unmashall.
+	typedef void (*ElemRstoreFunct)(T& dest, const void *srcdata);
+	/// Return object elem's size in bytes.
+	typedef u_int32_t (*ElemSizeFunct)(const T& elem);
+	/// Copy object elem's data to be persisted into a memory chunk 
+	/// referenced by dest. The dest memory is large enough. 
+	/// elem may not reside on a 
+	/// consecutive chunk of memory. This is also called marshal.
+	typedef void (*ElemCopyFunct)(void *dest, const T&elem);
+	typedef int (*ElemCompareFunct)(const T&a, const T&b);
+	/// Compares first num number of elements of sequence a and b, returns 
+	/// negative/0/positive value if a is less/equal/greater than b.
+	typedef int (*SequenceNCompareFunct)(const T *a, const T *b, 
+	    size_t num);
+	/// Compares sequence a and b, returns negative/0/positive
+	/// value if a is less/equal/greater than b.
+	typedef int (*SequenceCompareFunct)(const T *a, const T *b);
+	/// Return the sequence's number of elements.
+	typedef u_int32_t (*SequenceLenFunct)(const T *seqs);
+
+	/// Copy the sequence seqs's first num elements to seqd.
+	/// The sequence seqs of type T objects may not reside in a continuous
+	/// chunk of memory, but the seqd sequence points to a consecutive 
+	/// chunk of memory large enough to hold all objects from seqs.
+	/// And if T is a complex type, you should register your ElemCopyFunct
+	/// object marshalling manipulator
+	typedef void (*SequenceCopyFunct)(T *seqd, const T *seqs, size_t num);
+	//@}
+	
+	typedef T char_type;
+	typedef long int_type;
+
+	/// \name Interface compatible with std::string's char_traits.
+	/// Following are char_traits funcitons, which make this class 
+	/// char_traits compatiable, so that it can be used in 
+	/// std::basic_string template, and be manipulated by the c++ stl 
+	/// algorithms.
+	//@{
+	/// Assignone object to another.
+	static void  assign(T& left, const T& right)
+	{
+		if (inst_->assign_)
+			inst_->assign_(left, right);
+		else
+			left = right;
+	}
+
+	/// Check for equality of two objects.
+	static bool  eq(const T& left, const T& right)
+	{
+		if (inst_->elemcmp_)
+			return inst_->elemcmp_(left, right) == 0;
+		else
+			return left == right;
+	}
+
+	/// \brief Less than comparison.
+	///
+	/// Returns if object left is less than object right.
+	static bool  lt(const T& left, const T& right)
+	{
+		if (inst_->elemcmp_)
+			return inst_->elemcmp_(left, right) < 0;
+		else 
+			return left < right;
+	}
+
+	/// \brief Sequence comparison.
+	///
+	/// Compares the first cnt number of elements in the two 
+	/// sequences seq1 and seq2, returns negative/0/positive if seq1 is
+	/// less/equal/greater than seq2.
+	static int  compare(const T *seq1, const T *seq2, size_t cnt)
+	{
+		if (inst_->seqncmp_)
+			return inst_->seqncmp_(seq1, seq2, cnt);
+		else {
+			for (; 0 < cnt; --cnt, ++seq1, ++seq2)
+				if (!eq(*seq1, *seq2))
+					return (lt(*seq1, *seq2) ? -1 : +1);
+		}
+		return (0);
+	}
+
+	/// Returns the number of elements in sequence seq1. Note that seq1
+	/// may or may not end with a trailing '\0', it is completely user's
+	/// responsibility for this decision, though seq[0], seq[1],...
+	/// seq[length - 1] are all sequence seq's memory.
+	static size_t  length(const T *seq)
+	{
+		assert(inst_->seqlen_ != NULL);
+		return (size_t)inst_->seqlen_(seq);
+	}
+
+	/// Copy first cnt number of elements from seq2 to seq1.
+	static T * copy(T *seq1, const T *seq2, size_t cnt)
+	{
+		if (inst_->seqcpy_)
+			inst_->seqcpy_(seq1, seq2, cnt);
+		else {
+			T *pnext = seq1;
+			for (; 0 < cnt; --cnt, ++pnext, ++seq2)
+				assign(*pnext, *seq2);
+		}
+		return (seq1);
+	}
+
+	/// Find within the first cnt elements of sequence seq the position 
+	/// of element equal to elem.
+	static const T * find(const T *seq, size_t cnt, const T& elem)
+	{
+		for (; 0 < cnt; --cnt, ++seq)
+			if (eq(*seq, elem))
+				return (seq);
+		return (0);
+	}
+
+	/// \brief Sequence movement.
+	///
+	/// Move first cnt number of elements from seq2 to seq1, seq1 and seq2
+	/// may or may not overlap.
+	static T * move(T *seq1, const T *seq2, size_t cnt)
+	{
+		T *pnext = seq1;
+		if (seq2 < pnext && pnext < seq2 + cnt)
+			for (pnext += cnt, seq2 += cnt; 0 < cnt; --cnt)
+				assign(*--pnext, *--seq2);
+		else
+			for (; 0 < cnt; --cnt, ++pnext, ++seq2)
+				assign(*pnext, *seq2);
+		return (seq1);
+	}
+
+	/// Assign first cnt number of elements of sequence seq with the 
+	/// value of elem.
+	static T * assign(T *seq, size_t cnt, T elem)
+	{
+		T *pnext = seq;
+		for (; 0 < cnt; --cnt, ++pnext)
+			assign(*pnext, elem);
+		return (seq);
+	}
+
+	static T  to_char_type(const int_type& meta_elem)
+	{	// convert metacharacter to character
+		return ((T)meta_elem);
+	}
+
+	static int_type  to_int_type(const T& elem)
+	{	// convert character to metacharacter
+		return ((int_type)elem);
+	}
+
+	static bool  eq_int_type(const int_type& left,
+		const int_type& right)
+	{	// test for metacharacter equality
+		return (left == right);
+	}
+
+	static int_type  eof()
+	{	// return end-of-file metacharacter
+		return ((int_type)EOF);
+	}
+
+	static int_type  not_eof(const int_type& meta_elem)
+	{	// return anything but EOF
+		return (meta_elem != eof() ? (int_type)meta_elem : 
+		    (int_type)!eof());
+	}
+
+	//@}
+	
+	/// Factory method to create a singeleton instance of this class. 
+	/// The created object will be deleted by dbstl upon process exit.
+	inline static DbstlElemTraits *instance()
+	{
+		if (!inst_) {
+			inst_ = new DbstlElemTraits();
+			register_global_object(inst_);
+		}
+		return inst_;
+	}
+
+	/// \name Set/get functions for callback function pointers.
+	/// These are the setters and getters for each callback function 
+	/// pointers.
+	//@{
+	inline void set_restore_function(ElemRstoreFunct f)
+	{
+		restore_ = f;
+	}
+
+	inline ElemRstoreFunct get_restore_function() { return restore_; }
+
+	inline void set_assign_function(ElemAssignFunct f)
+	{
+		assign_ = f;
+	}
+
+	inline ElemAssignFunct get_assign_function() { return assign_; }
+
+	inline ElemSizeFunct get_size_function() { return size_; }
+
+	inline void set_size_function(ElemSizeFunct f) { size_ = f; }
+
+	inline ElemCopyFunct get_copy_function() { return copy_; }
+
+	inline void set_copy_function(ElemCopyFunct f) { copy_ = f; }
+
+	inline void set_sequence_len_function(SequenceLenFunct f)
+	{
+		seqlen_ = f;
+	}
+
+	inline SequenceLenFunct get_sequence_len_function() { return seqlen_; }
+
+	inline SequenceCopyFunct get_sequence_copy_function()
+	{
+		return seqcpy_;
+	}
+
+	inline void set_sequence_copy_function(SequenceCopyFunct f)
+	{
+		seqcpy_ = f;
+	}
+
+	inline void set_compare_function(ElemCompareFunct f)
+	{
+		elemcmp_ = f;
+	}
+
+	inline ElemCompareFunct get_compare_function()
+	{
+		return elemcmp_;
+	}
+
+	inline void set_sequence_compare_function(SequenceCompareFunct f)
+	{
+		seqcmp_ = f;
+	}
+
+	inline SequenceCompareFunct get_sequence_compare_function()
+	{
+		return seqcmp_;
+	}
+
+	inline void set_sequence_n_compare_function(SequenceNCompareFunct f)
+	{
+		seqncmp_ = f;
+	}
+
+	inline SequenceNCompareFunct get_sequence_n_compare_function()
+	{
+		return seqncmp_;
+	}
+	//@}
+
+	~DbstlElemTraits(){}
+protected:
+	inline DbstlElemTraits()
+	{
+		assign_ = NULL;
+		restore_ = NULL;
+		size_ = NULL;
+		copy_ = NULL;
+		seqlen_ = NULL;
+		seqcpy_ = NULL;
+		seqcmp_ = NULL;
+		seqncmp_ = NULL;
+		elemcmp_ = NULL;
+	}
+
+	static DbstlElemTraits *inst_;
+
+	// Data members to hold registered function pointers.
+	ElemAssignFunct assign_;
+	ElemRstoreFunct restore_;
+	ElemSizeFunct size_;
+	ElemCopyFunct copy_;
+	ElemCompareFunct elemcmp_;
+	SequenceCompareFunct seqcmp_;
+	SequenceNCompareFunct seqncmp_;
+	SequenceLenFunct seqlen_;
+	SequenceCopyFunct seqcpy_;
+}; //DbstlElemTraits
+//@} // dbstl_helper_classes
+
+template<typename T>
+DbstlElemTraits<T> *DbstlElemTraits<T>::inst_ = NULL;
+
+/** 
+\ingroup dbstl_helper_classes
+@{
+You can persist all bytes in a chunk of contiguous memory by constructing 
+an DbstlDbt object A(use malloc to allocate the required number of bytes for 
+A.data and copy the bytes to be stored into A.data, set other 
+fields as necessary) and store A into a container, e.g. db_vector<DbstlDbt>, 
+this stores the bytes rather than the object A into the underlying database.
+The DbstlDbt class can help you avoid memory leaks, 
+so it is strongly recommended that you use DbstlDbt rather than Dbt class.
+
+DbstlDbt derives from Dbt class, and it does an deep copy on copy construction 
+and assignment --by calling malloc to allocate its own memory and then 
+copying the bytes to it; Conversely the destructor will free the memory on 
+destruction if the data pointer is non-NULL. The destructor assumes the 
+memory is allocated via malloc, hence why you are required to call 
+malloc to allocate memory in order to use DbstlDbt. 
+
+DbstlDbt simply inherits all methods from Dbt with no extra 
+new methods except the constructors/destructor and assignment operator, so it 
+is easy to use. 
+
+In practice you rarely need to use DbstlDbt 
+or Dbt because dbstl enables you to store any complex 
+objects or primitive data. Only when you need to store raw bytes, 
+e.g. a bitmap, do you need to use DbstlDbt. 
+
+Hence, DbstlDbt is the right class to 
+use to store any object into Berkeley DB via dbstl without memory leaks.
+
+Don't free the memory referenced by DbstlDbt objects, it will be freed when the
+DbstlDbt object is destructed.
+
+Please refer to the two examples using DbstlDbt in 
+TestAssoc::test_arbitrary_object_storage and
+TestAssoc::test_char_star_string_storage member functions, 
+which illustrate how to correctly use DbstlDbt in order to store raw bytes.
+
+This class handles the task of allocating and de-allocating memory internally. 
+Although it can be used to store data which cannot be handled by the 
+DbstlElemTraits 
+class, in practice, it is usually more convenient to register callbacks in the 
+DbstlElemTraits class for the type you are storing/retrieving using dbstl.
+*/
+class DbstlDbt : public Dbt
+{
+	inline void deep_copy(const DbstlDbt &d)
+	{
+		u_int32_t len;
+		if (d.get_data() != NULL && d.get_size() > 0) {
+			if (d.get_flags() & DB_DBT_USERMEM)
+				len = d.get_ulen();
+			else
+				len = d.get_size();
+
+			set_data(DbstlMalloc(len));
+			memcpy(get_data(), d.get_data(), len);
+		}
+	}
+
+public:
+	/// Construct an object with an existing chunk of memory of size1 
+	/// bytes, refered by data1, 
+	DbstlDbt(void *data1, u_int32_t size1) : Dbt(data1, size1){}
+	DbstlDbt() : Dbt(){}
+	/// The memory will be free'ed by the destructor.
+	~DbstlDbt() 
+	{ 
+		free_mem();
+	}
+
+	/// This copy constructor does a deep copy.
+	DbstlDbt(const DbstlDbt &d) : Dbt(d) 
+	{
+		deep_copy(d);
+	}
+
+	/// The memory will be reallocated if neccessary. 
+	inline const DbstlDbt &operator = (const DbstlDbt &d)
+	{
+		ASSIGNMENT_PREDCOND(d)
+
+		if (d.get_data() != NULL && d.get_size() > 0) {
+			free_mem();
+			memcpy(this, &d, sizeof(d));
+		}
+
+		deep_copy(d);
+		return d;
+	}
+
+protected:
+	/// Users don't need to call this function.
+	inline void free_mem()
+	{
+		if (get_data()) {
+			free(get_data());
+			memset(this, 0, sizeof(*this));
+		}
+	}
+
+};
+//@} // dbstl_help_classes
+END_NS
+
+#endif // ! _DB_STL_UTILITY_H__
+
+
diff --git a/stl/dbstl_vector.h b/stl/dbstl_vector.h
new file mode 100644
index 0000000..cf26484
--- /dev/null
+++ b/stl/dbstl_vector.h
@@ -0,0 +1,3332 @@
+/*-
+ * See the file LICENSE for redistribution information.
+ *
+ * Copyright (c) 2009 Oracle.  All rights reserved.
+ *
+ * $Id$
+ */
+
+#ifndef _DB_STL_DB_VECTOR_H
+#define _DB_STL_DB_VECTOR_H
+
+#include "dbstl_common.h"
+#include "dbstl_dbc.h"
+#include "dbstl_element_ref.h"
+#include "dbstl_resource_manager.h"
+#include "dbstl_container.h"
+#include "dbstl_base_iterator.h"
+#include <list>
+#include <algorithm>
+
+START_NS(dbstl)
+
+using std::list;
+using std::istream;
+using std::ostream;
+using std::sort;
+
+#define TRandDbCursor RandDbCursor<T>
+
+// Forward Declarations
+// The default parameter is needed for the following code to work.
+template <class T, Typename value_type_sub = ElementRef<T> >
+class db_vector;
+template <class T, Typename value_type_sub = ElementRef<T> >
+class db_vector_iterator;
+template<class kdt, class ddt> class DbCursor;
+template<class ddt> class RandDbCursor;
+template<class ddt> class ElementRef;
+template <typename T, typename T2>
+class DbstlListSpecialOps;
+
+/// \ingroup dbstl_iterators
+/// @{
+/// \defgroup db_vector_iterators Iterator classes for db_vector.
+/// db_vector has two iterator classes --- db_vector_base_iterator and
+/// db_vector_iterator. The differences 
+/// between the two classes are that the db_vector_base_iterator
+/// can only be used to read its referenced value, so it is intended as
+/// db_vector's const iterator; While the other class allows both read and
+/// write access. If your access pattern is readonly, it is strongly 
+/// recommended that you use the const iterator because it is faster 
+/// and more efficient.
+/// The two classes have identical behaviors to std::vector::const_iterator and 
+/// std::vector::iterator respectively. Note that the common public member 
+/// function behaviors are described in the db_base_iterator section.
+/// \sa db_base_iterator
+//@{
+///////////////////////////////////////////////////////////////////////
+///////////////////////////////////////////////////////////////////////
+//
+// db_vector_base_iterator class template definition
+//
+// db_vector_base_iterator is the const_iterator class for db_vector, and
+// base class of db_vector_iterator -- iterator class for db_vector. Each
+// db_vector_base_iterator object owns one RandDbCursor<> cursor (1:1 map). 
+// On copy construction, the cursor is not duplicated, it is only created 
+// when it is really used (ie: lazily).
+// The value referred by this iterator is read only, can't be used to mutate
+// its referenced data element.
+//
+/// This class is the const iterator class for db_vector, and it is 
+/// inheirted by the db_vector_iterator class, which is the iterator
+/// class for db_vector.
+template <class T>
+class _exported db_vector_base_iterator : public db_base_iterator<T> 
+{
+protected:
+	// typedef's can't be put after where it is used.
+	typedef db_vector_base_iterator<T> self;
+	typedef db_recno_t index_type;
+	using db_base_iterator<T>::replace_current_key;
+public:
+	////////////////////////////////////////////////////////////////////
+	// 
+	// Begin public type definitions.
+	//
+	typedef T value_type;
+	typedef ptrdiff_t difference_type;
+	typedef difference_type distance_type;
+
+	/// This is the return type for operator[].
+	/// \sa value_type_wrap operator[](difference_type _Off) const
+	typedef value_type value_type_wrap;
+	typedef value_type& reference; 
+	typedef value_type* pointer;
+	// Use the STL tag, to ensure compatability with interal STL functions.
+	//
+	typedef std::random_access_iterator_tag iterator_category;
+	////////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////////
+	// Begin public constructors and destructor.
+	/// \name Constructors and destroctor
+	/// Do not construct iterators explictily using these constructors,
+	/// but call db_vector::begin() const to get an valid iterator.
+	/// \sa db_vector::begin() const
+	//@{
+	db_vector_base_iterator(const db_vector_base_iterator<T>& vi)
+	    : base(vi), pcsr_(vi.pcsr_), curpair_base_(vi.curpair_base_)
+	{
+		
+	}
+
+	explicit db_vector_base_iterator(db_container*powner,
+	    u_int32_t b_bulk_retrieval = 0, bool rmw = false, 
+	    bool directdbget = true, bool readonly = false)
+	    : base(powner, directdbget, readonly, b_bulk_retrieval, rmw),
+	    pcsr_(new TRandDbCursor(b_bulk_retrieval, rmw, directdbget))
+	{
+		
+	}
+
+	db_vector_base_iterator() : pcsr_(NULL)
+	{
+		
+	}
+
+	virtual ~db_vector_base_iterator()
+	{
+		this->dead_ = true;
+		if (pcsr_)
+			pcsr_->close();
+	}
+	//@}
+
+	////////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////////
+	//
+	// Begin functions that compare iterator positions.
+	//
+	// Use itr_status_ to do comparison if it is non-zero because end
+	// iterator does not have an underlying key/data pair, and call
+	// underlying cursor comparison otherwise.
+	/// \name Iterator comparison operators
+	/// The way to compare two iterators is to compare the index values 
+	/// of the two elements they point to. The iterator sitting on an 
+	/// element with less index is regarded to be smaller. And the invalid
+	/// iterator sitting after last element is greater than any other
+	/// iterators, because it is assumed to have an index equal to last 
+	/// element's index plus one; The invalid iterator sitting before first
+	/// element is less than any other iterators because it is assumed to
+	/// have an index -1.
+	//@{
+	/// \brief Equality comparison operator. 
+	///
+	/// Invalid iterators are equal; Valid iterators
+	/// sitting on the same key/data pair equal; Otherwise not equal.
+	/// \param itr The iterator to compare against.
+	/// \return True if this iterator equals to itr; False otherwise.
+	inline bool operator==(const self&itr) const
+	{
+		COMPARE_CHECK(itr)
+		if ((itr.itr_status_ == this->itr_status_) && 
+		    (this->itr_status_ == INVALID_ITERATOR_POSITION))
+		    return true;
+
+		if (this->itr_status_ != INVALID_ITERATOR_POSITION &&
+		    itr.itr_status_ != INVALID_ITERATOR_POSITION) {
+			return (pcsr_->compare((itr.pcsr_.base_ptr())) == 0);
+		}
+		return false;
+	}
+
+	/// \brief Unequal compare, identical to !operator(==itr)
+	/// \param itr The iterator to compare against.
+	/// \return False if this iterator equals to itr; True otherwise.
+	inline bool operator!=(const self&itr) const
+	{
+		return !(*this == itr) ;
+	}
+
+	// end() iterator is largest. If both are end() iterator return false.
+	/// \brief Less than comparison operator.
+	/// \param itr The iterator to compare against.
+	/// \return True if this iterator is less than itr.
+	inline bool operator < (const self& itr) const
+	{
+		bool ret;
+
+		if (this == &itr)
+			return false;
+
+		char after_last = base::IPT_AFTER_LAST,
+		    bef_fst = base::IPT_BEFORE_FIRST;
+
+		if (this->itr_status_ == INVALID_ITERATOR_POSITION &&
+		    this->inval_pos_type_ == after_last)
+			ret = false;
+		else if (this->itr_status_ == INVALID_ITERATOR_POSITION &&
+		    this->inval_pos_type_ == bef_fst)
+			ret = itr.inval_pos_type_ != bef_fst;
+		else { // This iterator is on an ordinary position.
+			if (itr.itr_status_ == INVALID_ITERATOR_POSITION &&
+			    itr.inval_pos_type_ == after_last)
+				ret = true;
+			else if (itr.itr_status_ == INVALID_ITERATOR_POSITION &&
+			    itr.inval_pos_type_ == bef_fst)
+				ret = false;
+			else { // Both iterators are on an ordinary position.
+				// By this stage all valid cases using
+				// INVALID_ITERATOR_POSITION have been dealt
+				// with.
+				assert((this->itr_status_ !=
+				    INVALID_ITERATOR_POSITION) &&
+				    (itr.itr_status_ != 
+				    INVALID_ITERATOR_POSITION));
+				ret = pcsr_->compare(
+				    (itr.pcsr_.base_ptr())) < 0;
+			}
+		}
+		return ret;
+	}
+
+	/// \brief Less equal comparison operator.
+	/// \param itr The iterator to compare against.
+	/// \return True if this iterator is less than or equal to itr.
+	inline bool operator <= (const self& itr) const
+	{
+		return !(this->operator>(itr));
+	}
+
+	/// \brief Greater equal comparison operator.
+	/// \param itr The iterator to compare against.
+	/// \return True if this iterator is greater than or equal to itr.
+	inline bool operator >= (const self& itr) const
+	{
+		return !(this->operator<(itr));
+	}
+
+	// end() iterator is largest. If both are end() iterator return false.
+	/// \brief Greater comparison operator.
+	/// \param itr The iterator to compare against.
+	/// \return True if this iterator is greater than itr.
+	inline bool operator > (const self& itr) const
+	{
+		bool ret;
+
+		if (this == &itr)
+			return false;
+
+		char after_last = base::IPT_AFTER_LAST,
+		    bef_fst = base::IPT_BEFORE_FIRST;
+
+		if (this->itr_status_ == INVALID_ITERATOR_POSITION &&
+		    this->inval_pos_type_ == after_last)
+			ret = itr.inval_pos_type_ != after_last;
+		else if (this->itr_status_ == INVALID_ITERATOR_POSITION &&
+		    this->inval_pos_type_ == bef_fst)
+			ret = false;
+		else { // This iterator is on an ordinary position.
+			if (itr.itr_status_ == INVALID_ITERATOR_POSITION &&
+			    itr.inval_pos_type_ == after_last)
+				ret = false;
+			else if (itr.itr_status_ == INVALID_ITERATOR_POSITION &&
+			    itr.inval_pos_type_ == bef_fst)
+				ret = true;
+			else { // Both iterators are on an ordinary position.
+				// By this stage all valid cases using
+				// INVALID_ITERATOR_POSITION have been dealt
+				// with.
+				assert((this->itr_status_ !=
+				    INVALID_ITERATOR_POSITION) &&
+				    (itr.itr_status_ != 
+				    INVALID_ITERATOR_POSITION));
+				ret = pcsr_->compare(
+				    (itr.pcsr_.base_ptr())) > 0;
+			}
+		}
+		return ret;
+	}
+	//@} // vctitr_cmp
+	////////////////////////////////////////////////////////////////////
+
+
+	////////////////////////////////////////////////////////////////////
+	//
+	// Begin functions that shift the iterator position.
+	//
+	/// \name Iterator movement operators.
+	/// When we talk about iterator movement, we think the 
+	/// container is a uni-directional range, represented by [begin, end),
+	/// and this is true no matter we are using iterators or reverse 
+	/// iterators. When an iterator is moved closer to "begin", we say it
+	/// is moved forward, otherwise we say it is moved backward.
+	//@{
+	/// \brief Pre-increment.
+	///
+	/// Move the iterator one element backward, so that
+	/// the element it sits on has a bigger index.
+	/// Use ++iter rather than iter++ where possible to avoid two useless
+	/// iterator copy constructions.
+	/// \return This iterator after incremented.
+	inline self& operator++()
+	{
+		move_by(*this, 1, false);
+		return *this;
+	}
+
+	/// \brief Post-increment.
+	/// Move the iterator one element backward, so that
+	/// the element it sits on has a bigger index.
+	/// Use ++iter rather than iter++ where possible to avoid two useless
+	/// iterator copy constructions.
+	/// \return A new iterator not incremented.
+	inline self operator++(int)
+	{
+		self itr(*this);
+		move_by(*this, 1, false);
+
+		return itr;
+	}
+
+	/// \brief Pre-decrement.
+	/// Move the iterator one element backward, so 
+	/// that the element it	sits on has a smaller index.
+	/// Use --iter rather than iter-- where possible to avoid two useless
+	/// iterator copy constructions.
+	/// \return This iterator after decremented.
+	inline self& operator--()
+	{
+		move_by(*this, 1, true);
+		return *this;
+	}
+
+	/// \brief Post-decrement.
+	///
+	/// Move the iterator one element backward, so 
+	/// that the element it	sits on has a smaller index.
+	/// Use --iter rather than iter-- where possible to avoid two useless
+	/// iterator copy constructions.
+	/// \return A new iterator not decremented.
+	inline self operator--(int)
+	{
+		self itr = *this;
+		move_by(*this, 1, true);
+		return itr;
+	}
+
+	/// \brief Assignment operator.
+	///
+	/// This iterator will point to the same key/data
+	/// pair as itr, and have the same configurations as itr.
+	/// \sa db_base_iterator::operator=
+	/// \param itr The right value of the assignment.
+	/// \return This iterator's reference.
+	inline const self& operator=(const self&itr)
+	{
+		ASSIGNMENT_PREDCOND(itr)
+		base::operator=(itr);
+		
+		if (pcsr_)
+			pcsr_->close();
+		pcsr_ = itr.pcsr_;
+		curpair_base_ = itr.curpair_base_;
+		return itr;
+	}
+
+	// Always move both iterator and cursor synchronously, keep iterators
+	// data synchronized.
+	/// Iterator movement operator.
+	/// Return another iterator by moving this iterator forward by n
+	/// elements.
+	/// \param n The amount and direction of movement. If negative, will
+	/// move forward by |n| element.
+	/// \return The new iterator at new position.
+	inline self operator+(difference_type n) const
+	{
+		self itr(*this);
+		move_by(itr, n, false);
+		return itr;
+	}
+
+	/// \brief Move this iterator backward by n elements.
+	/// \param n The amount and direction of movement. If negative, will
+	/// move forward by |n| element.
+	/// \return Reference to this iterator at new position.
+	inline const self& operator+=(difference_type n)
+	{
+		move_by(*this, n, false);
+		return *this;
+	}
+
+	/// \brief Iterator movement operator.
+	///
+	/// Return another iterator by moving this iterator backward by n
+	/// elements.
+	/// \param n The amount and direction of movement. If negative, will
+	/// move backward by |n| element.
+	/// \return The new iterator at new position.
+	inline self operator-(difference_type n) const
+	{
+		self itr(*this);
+		move_by(itr, n);
+
+		return itr;
+	}
+
+	/// \brief Move this iterator forward by n elements.
+	/// \param n The amount and direction of movement. If negative, will
+	/// move backward by |n| element.
+	/// \return Reference to this iterator at new position.
+	inline const self& operator-=(difference_type n)
+	{
+		move_by(*this, n);
+		return *this;
+	}
+	//@} //itr_movement
+
+	/// \brief Iterator distance operator.
+	///
+	/// Return the index difference of this iterator and itr, so if this
+	/// iterator sits on an element with a smaller index, this call will
+	/// return a negative number.
+	/// \param itr The other iterator to substract. itr can be the invalid
+	/// iterator after last element or before first element, their index
+	/// will be regarded as last element's index + 1 and -1 respectively.
+	/// \return The index difference.
+	difference_type operator-(const self&itr) const
+	{
+		difference_type p1, p2;
+
+		if (itr == end_itr_) {
+			if (itr.inval_pos_type_ == base::IPT_BEFORE_FIRST)
+				p2 = -1;
+			else if (
+			    this->inval_pos_type_ == base::IPT_AFTER_LAST) {
+				self pitr2(itr);
+				pitr2.open();
+				pitr2.last();
+				p2 = pitr2.get_current_index() + 1;
+			} else {
+				THROW0(InvalidIteratorException);
+			}
+		} else
+			p2 = itr.get_current_index();
+
+		if (*this == end_itr_) {
+			if (this->inval_pos_type_ == base::IPT_BEFORE_FIRST)
+				p1 = -1;
+			else if (
+			    this->inval_pos_type_ == base::IPT_AFTER_LAST) {
+				self pitr1(*this);
+				pitr1.open();
+				pitr1.last();
+				p1 = pitr1.get_current_index() + 1;
+			} else {
+				THROW0(InvalidIteratorException);
+			}
+		} else
+			p1 = this->get_current_index();
+
+		return (difference_type)(p1 - p2);
+	}
+
+	////////////////////////////////////////////////////////////////////
+	//
+	// Begin functions that retrieve values from the iterator.
+	//
+	// Each iterator has a dedicated cursor, and we keep the iterator
+	// and cursor synchronized all the time. The returned value is read
+	// only, can't be used to mutate its underlying data element.
+	//
+	/// \name Functions that retrieve values from the iterator.
+	//@{
+	/// \brief Dereference operator.
+	///
+	/// Return the reference to the cached data element, which is an 
+	/// ElementRef<T> object if T is a class type or an ElementHolder<T>
+	/// object if T is a C++ primitive data type.
+	/// The returned value can only be used to read its referenced 
+	/// element.
+	/// \return The reference to the element this iterator points to.
+	inline reference operator*() const
+	{
+		if (this->directdb_get_)
+			update_cur_pair();
+		return curpair_base_; // Return reference, no copy construction.
+	}
+
+	/// \brief Arrow operator.
+	///
+	/// Return the pointer to the cached data element, which is an 
+	/// ElementRef<T> object if T is a class type or an ElementHolder<T>
+	/// object if T is a C++ primitive data type.
+	/// The returned value can only be used to read its referenced 
+	/// element.
+	/// \return The address of the referenced object.
+	inline pointer operator->() const
+	{
+		if (this->directdb_get_)
+			update_cur_pair();
+		return &(curpair_base_);
+	}
+
+	/// \brief Iterator index operator.
+	///
+	/// If _Off not in a valid range, the returned value will be invalid.
+	/// Note that you should use a value_type_wrap type to hold the 
+	/// returned value.
+	/// \param _Off The valid index relative to this iterator.
+	/// \return Return the element which is at position *this + _Off.
+	/// The returned value can only be used to read its referenced 
+	/// element. 
+	inline value_type_wrap operator[](difference_type _Off) const
+	{
+		self itr(*this + _Off);
+		return itr.curpair_base_;
+	}
+	//@}
+	////////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////////
+	//
+	// Begin functions that are dbstl specific.
+	//
+	/// \name Functions that are dbstl specific.
+	//@{
+	/// \brief Get current index of within the vector.
+	///
+	/// Return the iterators current element's index (0 based). Requires
+	/// this iterator to be a valid iterator, not end_itr_.
+	/// \return current index of the iterator.
+	inline index_type get_current_index() const
+	{
+		return pcsr_->get_current_index() - 1;
+	}
+
+	/// \brief Iterator movement function.
+	///
+	/// Move this iterator to the index "n". If n is not in the valid 
+	/// range, this iterator will be an invalid iterator equal to end() 
+	/// iterator.
+	/// \param n target element's index.
+	/// \sa db_vector::end();
+	inline void move_to(index_type n) const
+	{
+		T d;
+		int ret;
+
+		this->itr_status_ = pcsr_->move_to(n + 1);
+		ret = pcsr_->get_current_data(d);
+		dbstl_assert(ret == 0);
+		if (this->itr_status_ == 0) 
+			update_cur_pair();
+	}
+
+	/// \brief Refresh iterator cached value.
+	/// \param from_db If not doing direct database get and this parameter
+	/// is true, we will retrieve data directly from db.
+	/// \sa db_base_iterator::refresh(bool).
+	virtual int refresh(bool from_db = true)
+	{
+		
+		if (from_db && !this->directdb_get_)
+			this->pcsr_->update_current_key_data_from_db(
+			    DbCursorBase::SKIP_NONE);
+		this->pcsr_->get_current_data(curpair_base_);
+		
+		return 0;
+	}
+
+	/// \brief Close underlying Berkeley DB cursor of this iterator.
+	/// \sa db_base_iterator::close_cursor() const
+	inline void close_cursor() const
+	{
+		this->pcsr_->close();
+	}
+
+	/// \brief Modify bulk buffer size. 
+	///
+	/// Bulk read is enabled when creating an
+	/// iterator, so you later can only modify the bulk buffer size
+	/// to another value, but can't enable/disable bulk read while an
+	/// iterator is already alive. 
+	/// \param sz The new size of the bulk read buffer of this iterator.
+	/// \return Returns true if succeeded, false otherwise.
+	/// \sa db_base_iterator::set_bulk_buffer(u_int32_t sz)
+	bool set_bulk_buffer(u_int32_t sz)
+	{
+		bool ret = this->pcsr_->set_bulk_buffer(sz);
+		if (ret)
+			this->bulk_retrieval_ = sz;
+		return ret;
+	}
+
+	/// \brief Get bulk retrieval buffer size in bytes.
+	/// \return Return current bulk buffer size, or 0 if bulk retrieval is
+	/// not enabled.
+	/// \sa db_base_iterator::get_bulk_bufsize()
+	u_int32_t get_bulk_bufsize()
+	{
+		this->bulk_retrieval_ = pcsr_->get_bulk_bufsize();
+		return this->bulk_retrieval_;
+	}
+	//@}
+	////////////////////////////////////////////////////////////////////
+
+protected:
+	typedef T value_type_base;
+	typedef db_base_iterator<T> base;
+	typedef index_type size_type;
+	typedef index_type key_type;
+	typedef T data_type;
+
+	// end_itr_ is always the same, so share it across iterator instances.
+	static self end_itr_;
+
+	////////////////// iterator data members //////////////////////////
+	//
+	mutable LazyDupCursor<TRandDbCursor> pcsr_;
+
+	void open() const
+	{
+		u_int32_t oflags = 0, oflags2 = 0;
+		int ret;
+		DbEnv *penv = this->owner_->get_db_env_handle();
+
+		oflags2 = this->owner_->get_cursor_open_flags();
+		if (!this->read_only_ && penv != NULL) {
+			BDBOP((penv->get_open_flags(&oflags)), ret);
+			// Open a writeable cursor when in CDS mode and not
+			// requesting a read only iterator.
+			if ((oflags & DB_INIT_CDB) != 0)
+				oflags2 |= DB_WRITECURSOR;
+		}
+
+		if (!this->pcsr_) {
+			
+			this->pcsr_.set_cursor(new TRandDbCursor(
+			    this->bulk_retrieval_, 
+			    this->rmw_csr_, this->directdb_get_));
+		}
+		this->itr_status_ = this->pcsr_->open(this->owner_, oflags2);
+	}
+
+	// Move the underlying Dbc* cursor to the first element.
+	//
+	inline int first() const
+	{
+		int ret = 0;
+
+		if ((ret = pcsr_->first()) == 0)
+			update_cur_pair();
+		else
+			this->itr_status_ = ret;
+
+		return ret;
+	}
+
+	// Move the underlying Dbc* cursor to the last element.
+	//
+	inline index_type last() const
+	{
+		index_type pos_index, lsz;
+
+		// last_index() will move the underlying cursor to last record.
+		lsz = pcsr_->last_index();
+		if (lsz > 0) {
+			pos_index = lsz - 1;
+			this->itr_status_ = 0;
+			update_cur_pair();
+		} else {
+			this->itr_status_ = INVALID_ITERATOR_POSITION;
+			pos_index = INVALID_INDEX;
+		}
+
+		return pos_index;
+	}
+
+	void set_curpair_base(const T& d)
+	{
+		curpair_base_ = d;
+	}
+
+	// Update curpair_base_'s data using current underlying key/data pair's
+	// value. Called on every iterator movement.
+	// Even if this iterator is invalid, this call is allowed, the
+	// default value of type T is returned.
+	//
+	virtual void update_cur_pair() const
+	{
+		this->pcsr_->get_current_data(curpair_base_);
+	}
+
+	// The 'back' parameter indicates whether to decrease or
+	// increase the index when moving. The default is to decrease.
+	// 
+	// Do not throw exceptions here because it is normal to iterate to
+	// "end()".
+	// Always move both iterator and cursor synchronously, keep iterators
+	// data synchronized.
+	void move_by(const self&itr, difference_type n, bool back = true) const
+	{
+		if (n == 0)
+			return;
+		if (!back)
+			n = -n;
+		if (itr == end_itr_) {
+			if (n > 0) { // Go back from end()
+				itr.open();
+				itr.last();
+				// Moving from end to the last position is
+				// considered one place.
+				if (n > 1) {
+					itr.itr_status_ = 
+					    itr.pcsr_->advance(-n + 1);
+					if (itr.itr_status_ == 
+					    INVALID_ITERATOR_POSITION)
+						itr.inval_pos_type_ = 
+						    base::IPT_BEFORE_FIRST;
+				}
+			} else
+				// Can't go further forward from the end.
+				return;
+
+		} else {
+			if (n == 1)
+				itr.itr_status_ = itr.pcsr_->prev();
+			else if (n == -1)
+				itr.itr_status_ = itr.pcsr_->next();
+			else
+				itr.itr_status_ = itr.pcsr_->advance(-n);
+		}
+
+		itr.update_cur_pair();
+		if (itr.itr_status_ != 0) {
+			if (n > 0)
+				itr.inval_pos_type_ = base::IPT_BEFORE_FIRST;
+			else
+				itr.inval_pos_type_ = base::IPT_AFTER_LAST;
+		}
+	}
+
+private:
+	// Current data element cached here.
+	mutable T curpair_base_;
+
+
+	friend class db_vector<T, ElementHolder<T> >;
+	friend class db_vector<T, ElementRef<T> >;
+	friend class DbCursor<index_type, T>;
+	friend class RandDbCursor<T>;
+	friend class ElementRef<T>;
+	friend class ElementHolder<T>;
+}; // db_vector_base_iterator<>
+
+template <Typename T>
+    db_vector_base_iterator<T> db_vector_base_iterator<T>::end_itr_;
+
+///////////////////////////////////////////////////////////////////////
+///////////////////////////////////////////////////////////////////////
+//
+// db_vector_iterator class template definition
+// This class is the iterator class for db_vector, its instances can
+// be used to mutate their referenced data element.
+//
+template <class T, Typename value_type_sub>
+class _exported db_vector_iterator : 
+    public db_vector_base_iterator<T> 
+{
+protected:
+	typedef db_vector_iterator<T, value_type_sub> self;
+	typedef db_recno_t index_type;
+	using db_base_iterator<T>::replace_current_key;
+public:
+	typedef T value_type;
+	typedef ptrdiff_t difference_type;
+	typedef difference_type distance_type;
+	typedef value_type_sub& reference;
+
+	/// This is the return type for operator[].
+	/// \sa value_type_wrap operator[](difference_type _Off) const
+	typedef value_type_sub value_type_wrap;
+	typedef value_type_sub* pointer;
+	// Use the STL tag, to ensure compatability with interal STL functions.
+	//
+	typedef std::random_access_iterator_tag iterator_category;
+
+	////////////////////////////////////////////////////////////////////
+	// Begin public constructors and destructor.
+	//
+	/// \name Constructors and destructor
+	/// Do not construct iterators explictily using these constructors,
+	/// but call db_vector::begin to get an valid iterator.
+	/// \sa db_vector::begin
+	//@{
+	db_vector_iterator(const db_vector_iterator<T, value_type_sub>& vi)
+	    : db_vector_base_iterator<T>(vi), 
+	    curpair_(vi.curpair_)
+	{
+		curpair_._DB_STL_SetIterator(this);
+	}
+
+	explicit db_vector_iterator(db_container*powner,
+	    u_int32_t b_bulk_retrieval = 0, bool brmw = false,
+	    bool directdbget = true, bool b_read_only = false)
+	    : db_vector_base_iterator<T>(powner, 
+	    b_bulk_retrieval, brmw, directdbget, b_read_only)
+	{
+		curpair_._DB_STL_SetIterator(this);
+		this->read_only_ = b_read_only;
+		this->rmw_csr_ = brmw;
+	}
+
+	db_vector_iterator() : db_vector_base_iterator<T>()
+	{
+		curpair_._DB_STL_SetIterator(this);
+	}
+
+	db_vector_iterator(const db_vector_base_iterator<T>&obj) 
+	    : db_vector_base_iterator<T>(obj)
+	{
+		curpair_._DB_STL_CopyData(*obj);
+	}
+
+	virtual ~db_vector_iterator()
+	{
+		this->dead_ = true;
+	}
+	//@}
+
+	////////////////////////////////////////////////////////////////////
+
+
+	////////////////////////////////////////////////////////////////////
+	//
+	// Begin functions that shift the iterator position.
+	//
+	// These functions are identical to those defined in 
+	// db_vector_base_iterator, but we have to redefine them here because
+	// the "self" have different definitions.
+	//
+	// Do not throw exceptions here because it is normal to iterate to
+	// "end()".
+	// Always move both iterator and cursor synchronously, keep iterators
+	// data synchronized.
+	//
+	/// \name Iterator movement operators.
+	/// These functions have identical behaviors and semantics as those of
+	/// db_vector_base_iterator, so please refer to equivalent in that 
+	/// class.
+	//@{
+	/// \brief Pre-increment.
+	/// \return This iterator after incremented.
+	/// \sa db_vector_base_iterator::operator++()
+	inline self& operator++()
+	{
+		move_by(*this, 1, false);
+		return *this;
+	}
+
+	/// \brief Post-increment.
+	/// \return A new iterator not incremented.
+	/// \sa db_vector_base_iterator::operator++(int)
+	inline self operator++(int)
+	{
+		self itr(*this);
+		move_by(*this, 1, false);
+
+		return itr;
+	}
+
+	/// \brief Pre-decrement.
+	/// \return This iterator after decremented.
+	/// \sa db_vector_base_iterator::operator--()
+	inline self& operator--()
+	{
+		move_by(*this, 1, true);
+		return *this;
+	}
+
+	/// \brief Post-decrement.
+	/// \return A new iterator not decremented.
+	/// \sa db_vector_base_iterator::operator--(int)
+	inline self operator--(int)
+	{
+		self itr = *this;
+		move_by(*this, 1, true);
+		return itr;
+	}
+
+	/// \brief Assignment operator.
+	///
+	/// This iterator will point to the same key/data
+	/// pair as itr, and have the same configurations as itr.
+	/// \param itr The right value of the assignment.
+	/// \return This iterator's reference.
+	/// \sa db_base_iterator::operator=(const self&)
+	inline const self& operator=(const self&itr)
+	{
+		ASSIGNMENT_PREDCOND(itr)
+		base::operator=(itr);
+
+		curpair_._DB_STL_CopyData(itr.curpair_);
+		return itr;
+	}
+
+	// Always move both iterator and cursor synchronously, keep iterators
+	// data synchronized.
+	/// \brief Iterator movement operator.
+	///
+	/// Return another iterator by moving this iterator backward by n
+	/// elements.
+	/// \param n The amount and direction of movement. If negative, will
+	/// move forward by |n| element.
+	/// \return The new iterator at new position.
+	/// \sa db_vector_base_iterator::operator+(difference_type n) const
+	inline self operator+(difference_type n) const
+	{
+		self itr(*this);
+		move_by(itr, n, false);
+		return itr;
+	}
+
+	/// \brief Move this iterator backward by n elements.
+	/// \param n The amount and direction of movement. If negative, will
+	/// move forward by |n| element.
+	/// \return Reference to this iterator at new position.
+	/// \sa db_vector_base_iterator::operator+=(difference_type n) 
+	inline const self& operator+=(difference_type n)
+	{
+		move_by(*this, n, false);
+		return *this;
+	}
+
+	/// \brief Iterator movement operator.
+	///
+	/// Return another iterator by moving this iterator forward by n
+	/// elements.
+	/// \param n The amount and direction of movement. If negative, will
+	/// move backward by |n| element.
+	/// \return The new iterator at new position.
+	/// \sa db_vector_base_iterator::operator-(difference_type n) const
+	inline self operator-(difference_type n) const
+	{
+		self itr(*this);
+		move_by(itr, n);
+
+		return itr;
+	}
+
+	/// \brief Move this iterator forward by n elements.
+	/// \param n The amount and direction of movement. If negative, will
+	/// move backward by |n| element.
+	/// \return Reference to this iterator at new position.
+	/// \sa db_vector_base_iterator::operator-=(difference_type n) 
+	inline const self& operator-=(difference_type n)
+	{
+		move_by(*this, n);
+		return *this;
+	}
+	//@} // itr_movement
+
+	/// \brief Iterator distance operator.
+	///
+	/// Return the index difference of this iterator and itr, so if this
+	/// iterator sits on an element with a smaller index, this call will
+	/// return a negative number.
+	/// \param itr The other iterator to substract. itr can be the invalid
+	/// iterator after last element or before first element, their index
+	/// will be regarded as last element's index + 1 and -1 respectively.
+	/// \return The index difference.
+	/// \sa db_vector_base_iterator::operator-(const self& itr) const
+	difference_type operator-(const self&itr) const
+	{
+		return base::operator-(itr);
+	}
+	////////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////////
+	//
+	// Begin functions that retrieve values from the iterator.
+	//
+	// Each iterator has a dedicated cursor, and we keep the iterator
+	// and cursor synchronized all the time. The return value can be used
+	// to mutate its referenced data element. If directdb_get_ is true(the
+	// default value), users must call element._DB_STL_SaveElement() to 
+	// store the changes they made to the data element before a next call 
+	// of this function, otherwise the change is lost.
+	//
+	/// \name Functions that retrieve values from the iterator.
+	//@{
+	/// \brief Dereference operator.
+	///
+	/// Return the reference to the cached data element, which is an 
+	/// ElementRef<T> object if T is a class type or an ElementHolder<T>
+	/// object if T is a C++ primitive data type.
+	/// The returned value can be used to read or update its referenced 
+	/// element.
+	/// \return The reference to the element this iterator points to.
+	inline reference operator*() const
+	{
+		if (this->directdb_get_)
+			update_cur_pair();
+		return curpair_; // Return reference, no copy construction.
+	}
+
+	/// \brief Arrow operator.
+	///
+	/// Return the pointer to the cached data element, which is an 
+	/// ElementRef<T> object if T is a class type or an ElementHolder<T>
+	/// object if T is a C++ primitive data type.
+	/// The returned value can be used to read or update its referenced 
+	/// element.
+	/// \return The address of the referenced object.
+	inline pointer operator->() const
+	{
+		if (this->directdb_get_)
+			update_cur_pair();
+		return &curpair_;
+	}
+
+	// We can't return reference here otherwise we are returning an 
+	// reference to an local object.
+	/// \brief Iterator index operator.
+	///
+	/// If _Off not in a valid range, the returned value will be invalid.
+	/// Note that you should use a value_type_wrap type to hold the 
+	/// returned value.
+	/// \param _Off The valid index relative to this iterator.
+	/// \return Return the element which is at position *this + _Off, 
+	/// which is an ElementRef<T> object if T is a class type or
+	/// an ElementHolder<T> object if T is a C++ primitive data type.
+	/// The returned value can be used to read or update its referenced 
+	/// element. 
+	inline value_type_wrap operator[](difference_type _Off) const
+	{
+		self *itr = new self(*this + _Off);
+		
+		value_type_sub ref(itr->curpair_);
+		ref._DB_STL_SetDelItr();
+		return ref;
+	}
+	//@} // funcs_val
+	////////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////////
+	//
+	// Begin dbstl specific functions.
+	//
+	/// \brief Refresh iterator cached value.
+	/// \param from_db If not doing direct database get and this parameter
+	/// is true, we will retrieve data directly from db.
+	/// \sa db_base_iterator::refresh(bool)
+	virtual int refresh(bool from_db = true)
+	{
+		T d;
+
+		if (from_db && !this->directdb_get_)
+			this->pcsr_->update_current_key_data_from_db(
+			    DbCursorBase::SKIP_NONE);
+		this->pcsr_->get_current_data(d);
+		curpair_._DB_STL_SetData(d);
+		this->set_curpair_base(d);
+		return 0;
+	}
+	////////////////////////////////////////////////////////////////////
+
+protected:
+	typedef T value_type_base;
+	typedef db_vector_base_iterator<T> base;
+	typedef index_type size_type;
+	typedef index_type key_type;
+	typedef T data_type;
+	typedef db_vector<T, value_type_sub> OwnerType;
+
+	friend class db_vector<T, value_type_sub>;
+	friend class DbCursor<index_type, T>;
+	friend class RandDbCursor<T>;
+	friend class ElementRef<T>;
+	friend class ElementHolder<T>;
+
+	// The data item this iterator currently points to. It is updated
+	// on every iterator movement. By default directdb_get_ member is true
+	// (can be set to false via container's begin() method), so whenever 
+	// operator */-> is called, it is retrieved from db, to support 
+	// concurrency.
+	mutable value_type_sub curpair_;
+
+	virtual void delete_me() const
+	{
+		if (!this->dead_)
+			delete this;
+	}
+
+	virtual self* dup_itr() const
+	{
+		self *itr = new self(*this);
+		// The curpair_ of itr does not delete itr, the independent
+		// one does.
+		// itr->curpair_._DB_STL_SetDelItr(); 
+		return itr;
+	}
+
+	// Replace the current key/data pair's data with d. Can only be called
+	// by non-const iterator. Normally internal functions do not wrap
+	// transactions, but replace_current is used in assignment by the user
+	// so it needs to be wrapped.
+	virtual int replace_current(const T& d)
+	{
+		int ret = 0;
+
+		if (this->read_only_) {
+			THROW(InvalidFunctionCall, (
+"replace_current can't be called via a readonly iterator."));
+		}
+		ret = this->pcsr_->replace(d);
+
+		return ret;
+	}
+
+	// This function is part of the db_base_iterator interface, but
+	// is not valid for db_vector_iterator.
+	virtual int replace_current_key(const T&) {
+		THROW(InvalidFunctionCall, (
+"replace_current_key not supported by db_vector_iterator<>"));
+	}
+
+	// Update curpair_'s data using current underlying key/data pair's
+	// value. Called on every iterator movement.
+	// Even if this iterator is invalid, this call is allowed, the
+	// default value of type T is returned.
+	//
+	virtual void update_cur_pair() const
+	{
+		T t;
+
+		this->pcsr_->get_current_data(t);
+		curpair_._DB_STL_CopyData(t);
+		base::update_cur_pair();
+	}
+
+
+}; // db_vector_iterator
+//@} // db_vector_iterators
+//@} // dbstl_iterators
+
+// These operators make "n + itr" expressions valid. Without it, you can only
+// use "itr + n"
+template <Typename T>
+db_vector_base_iterator<T> operator+(typename db_vector_base_iterator<T>::
+    difference_type n, db_vector_base_iterator<T> itr)
+{
+	db_vector_base_iterator<T> i2 = itr;
+
+	i2 += n;
+	return i2;
+}
+
+template <Typename T, Typename value_type_sub>
+db_vector_iterator<T, value_type_sub> operator+(
+    typename db_vector_iterator<T, value_type_sub>::
+    difference_type n, db_vector_iterator<T, value_type_sub> itr)
+{
+	db_vector_iterator<T, value_type_sub> i2 = itr;
+
+	i2 += n;
+	return i2;
+}
+
+template <Typename iterator, Typename iterator2>
+db_reverse_iterator<iterator, iterator2> operator+(typename
+    db_reverse_iterator<iterator, iterator2>::difference_type n,
+    db_reverse_iterator<iterator, iterator2> itr)
+{
+	db_reverse_iterator<iterator, iterator2> i2 = itr;
+	// The db_reverse_iterator<iterator>::operator+ will substract
+	// n in it, we pass the + here.
+	//
+	i2 += n;
+	return i2;
+}
+
+/// \ingroup dbstl_containers
+//@{
+////////////////////////////////////////////////////////////////////////
+////////////////////////////////////////////////////////////////////////
+//
+// db_vector class template definition
+//
+/// The db_vector class has the union set of public member functions as
+/// std::vector, std::deque and std::list, and each method has identical
+/// default semantics to that in the std equivalent containers.
+/// The difference is that the data is maintained using a Berkeley DB database
+/// as well as some Berkeley DB related extensions.
+/// \param T The type of data to store.
+/// \param value_type_sub If T is a class/struct type, do not specify anything
+/// for this parameter; Otherwise, specify ElementHolder<T> to it.
+/// Database(dbp) and environment(penv) handle requirement(applies for all 
+/// constructors of this class template):
+/// dbp must meet the following requirement:
+/// 1. dbp must be a DB_RECNO type of database handle.
+/// 2. DB_THREAD must be set to dbp's open flags.
+/// 3. An optional flag DB_RENUMBER is required if the container object
+/// is supposed to be a std::vector or std::deque equivalent; Not 
+/// required if it is a std::list equivalent. But dbstl will not check
+/// whether DB_RENUMBER is set to this database handle. 
+/// Setting DB_RENUMBER will cause the index values of all elements in
+/// the underlying databse to be maintained consecutive and in order, 
+/// which involves potentially a lot of work because many indices may
+/// be updated. 
+/// See the db_container(Db*, DbEnv*) for more information about the two
+/// parameters.
+/// \sa db_container db_container(Db*, DbEnv*) db_container(const db_container&)
+//
+template <Typename T, Typename value_type_sub>
+class _exported db_vector: public db_container
+{
+private:
+	typedef db_vector<T, value_type_sub> self;
+	typedef db_recno_t index_type;
+public:
+	typedef T value_type;
+	typedef value_type_sub value_type_wrap;
+	typedef value_type_sub* pointer;
+	typedef db_vector_iterator<T, value_type_sub> iterator;
+	typedef db_vector_base_iterator<T> const_iterator;
+	typedef index_type size_type;
+	typedef db_reverse_iterator<iterator, const_iterator> reverse_iterator;
+	typedef const value_type_sub* const_pointer;
+	typedef db_reverse_iterator<const_iterator, iterator> 
+	    const_reverse_iterator;
+
+	typedef typename value_type_sub::content_type const_value_type;
+
+	// We don't use value_type_sub& as a reference type here because 
+	// we created a local iterator object in operator[], and we must keep
+	// an active cursor on the key/data pair. Thus operator[] needs to 
+	// return an object rather than a reference to a local object.
+	typedef value_type_sub reference;
+
+	// We can't return reference here because we are using a local iterator.
+	typedef const_value_type const_reference;
+	typedef ptrdiff_t difference_type;
+
+	/////////////////////////////////////////////////////////////////////
+	// Begin functions that create iterators.
+	/// \name Iterator functions.
+	//@{
+	/// \brief Create a read-write or read-only iterator. 
+	///
+	/// We allow users to create a readonly 
+	/// iterator here so that they don't have to use a const container 
+	/// to create a const_iterator. But using const_iterator
+	/// is faster. The flags set via db_container::set_cursor_oflags() is
+	/// used as the cursor open flags.
+	/// \param rmw Whether this iterator will open a Berkeley DB
+	/// cursor with DB_RMW flag set. If the iterator is used to read a 
+	/// key/data pair, then update it and store back to db, it is good 
+	/// to set the DB_RMW flag, by specifying RMWItrOpt::read_modify_write()
+	/// If you don't want to set the DB_RMW flag, specify 
+	/// RMWItrOpt::no_read_modify_write(), which is the default behavior.
+	/// \param readonly Whether the iterator is created as a readonly 
+	/// iterator. Read only iterators can not update its underlying 
+	/// key/data pair.
+	/// \param bulk_read Whether read database key/data pairs in bulk, by
+	/// specifying DB_MULTIPLE_KEY flag to underlying cursor's Dbc::get 
+	/// function. Only readonly iterators can do bulk retrieval, if
+	/// iterator is not read only, this parameter is ignored. Bulk 
+	/// retrieval can accelerate reading speed because each database read
+	/// operation will read many key/data pairs, thus saved many database
+	/// read operations. The default bulk buffer size is 32KB, you can 
+	/// set your desired bulk buffer size by specifying 
+	/// BulkRetrievalOpt::bulk_retrieval(your_bulk_buffer_size); 
+	/// If you don't want bulk retrieval, set 
+	/// BulkRetrievalItrOpt::no_bulk_retrieval() as the real parameter.
+	/// \param directdb_get Whether always read key/data pair from backing
+	/// db rather than using the value cached in the iterator. The current
+	/// key/data pair is cached in the iterator and always kept updated on
+	/// iterator movement, but in some extreme conditions, errors can 
+	/// happen if you use cached key/data pairs without always refreshing
+	/// them from database. By default we are always reading from database
+	/// when we are accessing the data the iterator sits on, except when 
+	/// we are doing bulk retrievals. But your application can gain extra
+	/// performance promotion if you can set this flag to false.
+	/// \return The created iterator.
+	/// \sa db_container::set_cursor_oflags();
+	iterator begin(ReadModifyWriteOption rmw = 
+	    ReadModifyWriteOption::no_read_modify_write(),
+	    bool readonly = false, BulkRetrievalOption bulk_read =
+	    BulkRetrievalOption::no_bulk_retrieval(),
+	    bool directdb_get = true)
+	{
+		bool b_rmw;
+		u_int32_t bulk_retrieval;
+
+		bulk_retrieval = 0;
+		b_rmw = (rmw == ReadModifyWriteOption::read_modify_write());
+		if (readonly && b_rmw)
+			b_rmw = false;
+		// Bulk only available to readonly iterators.
+		if (readonly && bulk_read ==
+		    BulkRetrievalOption::BulkRetrieval)
+			bulk_retrieval = bulk_read.bulk_buf_size();
+
+		iterator itr((db_container*)this, bulk_retrieval, b_rmw,
+		    directdb_get, readonly);
+
+		open_itr(itr, readonly);
+		itr.first();
+
+		return itr;
+	}
+
+	/// \brief Create a const iterator.
+	///
+	/// The created iterator can only be used to read its referenced
+	/// data element. Can only be called when using a const reference to
+	/// the contaienr object. The parameters have identical meanings and 
+	/// usage to those of the other non-const begin function.
+	/// \param bulkretrieval Same as that of 
+	/// begin(ReadModifyWrite, bool, BulkRetrievalOption, bool);
+	/// \param directdb_get Same as that of
+	/// begin(ReadModifyWrite, bool, BulkRetrievalOption, bool);
+	/// \return The created const iterator.
+	/// \sa begin(ReadModifyWrite, bool, BulkRetrievalOption, bool);
+	const_iterator begin(BulkRetrievalOption bulkretrieval =
+	    (BulkRetrievalOption::no_bulk_retrieval()),
+	    bool directdb_get = true) const
+	{
+		u_int32_t b_bulk_retrieval = (bulkretrieval ==
+		    BulkRetrievalOption::BulkRetrieval) ?
+		    bulkretrieval.bulk_buf_size() : 0;
+
+		const_iterator itr((db_container*)this, b_bulk_retrieval, 
+			false, directdb_get, true);
+
+		open_itr(itr, true);
+		itr.first();
+
+		return itr;
+	}
+	
+	/// \brief Create an open boundary iterator.
+	/// \return Returns an invalid iterator denoting the position after 
+	/// the last valid element of the container.
+	inline iterator end()
+	{
+		end_itr_.owner_ = (db_container*)this;
+		end_itr_.inval_pos_type_ = db_base_iterator<T>::IPT_AFTER_LAST;
+ 		return end_itr_;
+	}
+
+	/// \brief Create an open boundary iterator.
+	/// \return Returns an invalid const iterator denoting the position 
+	/// after the last valid element of the container.
+	inline const_iterator end() const
+	{
+		end_itr_.owner_ = (db_container*)this;
+		end_itr_.inval_pos_type_ = db_base_iterator<T>::IPT_AFTER_LAST;
+ 		return end_itr_;
+	}
+
+	/// \brief Create a reverse iterator.
+	///
+	/// This function creates a reverse iterator initialized to sit on the
+	/// last element in the underlying database, and can be used to 
+	/// read/write. The meaning and usage of
+	/// its parameters are identical to the above begin function.
+	/// \param rmw Same as that of 
+	/// begin(ReadModifyWrite, bool, BulkRetrievalOption, bool);
+	/// \param bulk_read Same as that of 
+	/// begin(ReadModifyWrite, bool, BulkRetrievalOption, bool);
+	/// \param directdb_get Same as that of
+	/// begin(ReadModifyWrite, bool, BulkRetrievalOption, bool);
+	/// \param readonly Same as that of 
+	/// begin(ReadModifyWrite, bool, BulkRetrievalOption, bool);
+	/// \return The created iterator.
+	/// \sa begin(ReadModifyWrite, bool, BulkRetrievalOption, bool);
+	reverse_iterator rbegin(
+	    ReadModifyWriteOption rmw = 
+	    ReadModifyWriteOption::no_read_modify_write(),
+	    bool readonly = false, BulkRetrievalOption bulk_read =
+	    BulkRetrievalOption::no_bulk_retrieval(),
+	    bool directdb_get = true)
+	{
+		u_int32_t bulk_retrieval = 0;
+
+		reverse_iterator itr(end());
+		itr.rmw_csr_ = 
+		    (rmw == (ReadModifyWriteOption::read_modify_write()));
+		itr.directdb_get_ = directdb_get;
+		itr.read_only_ = readonly;
+		itr.owner_ = (db_container*)this;
+
+		// Bulk only available to readonly iterators.
+		if (readonly && 
+		    bulk_read == BulkRetrievalOption::BulkRetrieval)
+			bulk_retrieval = bulk_read.bulk_buf_size();
+		itr.bulk_retrieval_ = bulk_retrieval;
+
+		return itr;
+	}
+
+	/// \brief Create a const reverse iterator.
+	///
+	/// This function creates a const reverse iterator initialized to sit
+	/// on the last element in the backing database, and can only read the
+	/// element, it is only available to const db_vector containers. 
+	/// The meaning and usage of its parameters are identical as above.
+	/// \param bulkretrieval Same as that of 
+	/// begin(ReadModifyWrite, bool, BulkRetrievalOption, bool);
+	/// \param directdb_get Same as that of
+	/// begin(ReadModifyWrite, bool, BulkRetrievalOption, bool);
+	/// \return The created iterator.
+	/// \sa begin(ReadModifyWrite, bool, BulkRetrievalOption, bool);
+	const_reverse_iterator rbegin(BulkRetrievalOption bulkretrieval =
+	    BulkRetrievalOption(BulkRetrievalOption::no_bulk_retrieval()),
+	    bool directdb_get = true) const
+	{
+		const_reverse_iterator itr(end());
+		itr.bulk_retrieval_ = 
+		    (bulkretrieval == (BulkRetrievalOption::BulkRetrieval) ?
+		    bulkretrieval.bulk_buf_size() : 0);
+
+		itr.directdb_get_ = directdb_get;
+		itr.read_only_ = true;
+		itr.owner_ = (db_container*)this;
+
+		return itr;
+	}
+
+	/// \brief Create an open boundary iterator.
+	/// \return Returns an invalid iterator denoting the position 
+	/// before the first valid element of the container.
+	inline reverse_iterator rend()  
+	{
+		reverse_iterator itr; // No cursor created.
+
+		itr.itr_status_ = INVALID_ITERATOR_POSITION;
+		itr.owner_ = (db_container*)this;
+		itr.inval_pos_type_ = db_base_iterator<T>::IPT_BEFORE_FIRST;
+		return itr;
+	}
+
+	/// \brief Create an open boundary iterator.
+	/// \return Returns an invalid const iterator denoting the position 
+	/// before the first valid element of the container. 
+	inline const_reverse_iterator rend() const
+	{
+		const_reverse_iterator itr; // No cursor created.
+
+		itr.itr_status_ = INVALID_ITERATOR_POSITION;
+		itr.owner_ = (db_container*)this;
+		itr.inval_pos_type_ = db_base_iterator<T>::IPT_BEFORE_FIRST;
+		return itr;
+	}
+	//@} // iterator_funcs
+	/////////////////////////////////////////////////////////////////////
+
+	/// \brief Get container size.
+	/// This function supports auto-commit.
+	// All container methods using internal working iterators can be used
+	// to implement autocommit if no DB operations can be directly used,
+	// because the work iterator is not supposed to point to a specific
+	// record before reopening it.
+	/// \return Return the number of elements in this container.
+	/// \sa http://www.cplusplus.com/reference/stl/vector/size.html
+	size_type size() const
+	{
+		index_type sz;
+
+		try {
+			this->begin_txn();
+			const_iterator derefitr;
+			init_itr(derefitr);
+			open_itr(derefitr, true);
+			sz = derefitr.last() + 1;
+			this->commit_txn();
+			return (size_type)sz; // Largest index is the size.
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+	}
+
+	/// \name Huge return
+	/// These two functions return 2^30, denoting a huge number that does
+	/// not overflow, because dbstl does not have to manage memory space.
+	/// But the return value is not the real limit, see the Berkeley DB 
+	/// database limits for the limits.
+	//@{
+	/// Get max size.
+	/// The returned size is not the actual limit of database. See the
+	/// Berkeley DB limits to get real max size.
+	/// \return A meaningless huge number.
+	inline size_type max_size() const
+	{
+		return SIZE_T_MAX;
+	}
+
+	/// Get capacity.
+	inline size_type capacity() const
+	{
+		return SIZE_T_MAX;
+	}
+	//@}
+
+	/// Returns whether this container is empty.
+	/// \return True if empty, false otherwise.
+	inline bool empty() const
+	{
+		const_iterator itr = begin();
+		return itr.itr_status_ == INVALID_ITERATOR_POSITION;
+	}
+
+	/////////////////////////////////////////////////////////////////////
+	// Begin element access functions.
+	//
+	/// \name Element access functions.
+	/// The operator[] and at() only come from std::vector and std::deque, 
+	/// If you are using db_vector as std::list, you don't have
+	/// to set DB_RENUMBER flag to the backing database handle, and you get
+	/// better performance, but at the same time you can't use these 
+	/// functions. Otherwise if you have set the DB_RENUMBER flag to the 
+	/// backing database handle, you can use this function though it is an
+	/// std::list equivalent.
+	//@{
+	/// Index operator, can act as both a left value and a right value.
+	/// \param n The valid index of the vector.
+	/// \return The reference to the element at specified position.
+	inline reference operator[](index_type n)
+	{
+		iterator derefitr, *pitr;
+
+		init_itr(derefitr);
+		open_itr(derefitr);
+		if (n == INVALID_INDEX)
+			n = derefitr.last();
+		derefitr.move_to(n);
+		
+		pitr = new iterator(derefitr);
+		reference ref(pitr->curpair_);
+		ref._DB_STL_SetDelItr();
+		return ref;
+	}
+
+	/// \brief Read only index operator.
+	///
+	/// Only used as a right value, no need for assignment capability.
+	/// The return value can't be used to update the element.
+	/// \param n The valid index of the vector.
+	/// \return The const reference to the element at specified position.
+	inline const_reference operator[](index_type n) const
+	{
+		const_iterator derefitr;
+
+		init_itr(derefitr);
+		open_itr(derefitr);
+		if (n == INVALID_INDEX)
+			n = derefitr.last();
+		derefitr.move_to(n);
+
+		// _DB_STL_value returns a reference
+		return (*derefitr);
+	}
+
+	/// \brief Index function.
+	/// \param n The valid index of the vector.
+	/// \return The reference to the element at specified position, can 
+	/// act as both a left value and a right value.
+	/// \sa http://www.cplusplus.com/reference/stl/vector/at.html
+	inline reference at(index_type n)
+	{
+		return (*this)[n];
+	}
+
+	/// \brief Read only index function.
+	///
+	/// Only used as a right value, no need for assignment capability.
+	/// The return value can't be used to update the element.
+	/// \param n The valid index of the vector.
+	/// \return The const reference to the element at specified position.
+	/// \sa http://www.cplusplus.com/reference/stl/vector/at.html
+	inline const_reference at(index_type n) const
+	{
+	       return (*this)[n];
+	}
+
+	/// Return a reference to the first element.
+	/// \return Return a reference to the first element.
+	/// \sa http://www.cplusplus.com/reference/stl/vector/front.html 
+	inline reference front()
+	{
+		iterator itr, *pitr;
+
+		init_itr(itr);
+		open_itr(itr);
+		itr.first();
+		
+		pitr = new iterator(itr);
+		reference ref(pitr->curpair_);
+		ref._DB_STL_SetDelItr();
+		return ref;
+	}
+
+	/// \brief Return a const reference to the first element. 
+	///
+	/// The return value can't be used to update the element.
+	/// \return Return a const reference to the first element. 
+	/// \sa http://www.cplusplus.com/reference/stl/vector/front.html 
+	inline const_reference front() const
+	{
+	 	const_iterator itr;
+
+		init_itr(itr);
+		open_itr(itr);
+		itr.first();
+		return (*itr);
+	}
+
+	/// Return a reference to the last element.
+	/// \return Return a reference to the last element.
+	/// \sa http://www.cplusplus.com/reference/stl/vector/back.html
+	inline reference back()
+	{
+		iterator itr, *pitr;
+
+		init_itr(itr);
+		open_itr(itr);
+		itr.last();
+		
+		pitr = new iterator(itr);
+		reference ref(pitr->curpair_);
+		ref._DB_STL_SetDelItr();
+		return ref;
+	}
+
+	/// \brief Return a reference to the last element. 
+	///
+	/// The return value can't be used to update the element.
+	/// \return Return a reference to the last element. 
+	/// \sa http://www.cplusplus.com/reference/stl/vector/back.html
+	inline const_reference back() const
+	{
+		const_iterator itr;
+
+		init_itr(itr);
+		open_itr(itr);
+		itr.last();
+		return (*itr);
+	}
+	//@}
+
+	////////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////////
+	//
+	// Begin db_vector constructors and destructor. 
+	/// \brief Constructor.
+	///
+	/// Note that we do not need an allocator in db-stl containser, but
+	/// we need backing up Db* and DbEnv*, and we have to verify that the
+	/// passed in bdb handles are valid for use by the container class.
+	/// See class detail for handle requirement.
+	/// \param dbp The same as that of db_container(Db*, DbEnv*);
+	/// \param penv The same as that of db_container(Db*, DbEnv*);
+	/// \sa db_container(Db*, DbEnv*);
+	//
+	explicit db_vector(Db* dbp = NULL, DbEnv *penv = NULL)
+	    : base(dbp, penv)
+	{
+		const char *errmsg;
+
+		this->open_db_handles(dbp, penv, DB_RECNO, DB_CREATE |
+		    DB_THREAD, DB_RENUMBER);
+		if ((errmsg = verify_config(dbp, penv)) != NULL) {
+			THROW(InvalidArgumentException, ("Db*", errmsg));
+		}
+		this->set_db_handle_int(dbp, penv);
+	}
+
+	/// \brief Constructor.
+	///
+	/// This function supports auto-commit. 
+	/// Insert n elements of T type into the database, the value of the 
+	/// elements is the default value or user set value.
+	/// See class detail for handle requirement.
+	/// \param n The number of elements to insert.
+	/// \param val The value of elements to insert.
+	/// \param dbp The same as that of db_container(Db*, DbEnv*);
+	/// \param penv The same as that of db_container(Db*, DbEnv*);
+	/// \sa db_vector(Db*, DbEnv*); db_container(Db*, DbEnv*);
+	explicit db_vector(size_type n, const T& val = T(), Db* dbp = NULL,
+	    DbEnv *penv = NULL) : base(dbp, penv)
+	{
+		size_type i;
+		const char *errmsg;
+
+		this->open_db_handles(dbp, penv, DB_RECNO, DB_CREATE |
+		    DB_THREAD, DB_RENUMBER);
+		if ((errmsg = verify_config(dbp, penv)) != NULL) {
+			THROW(InvalidArgumentException, ("Db*", errmsg));
+		}
+		this->set_db_handle_int(dbp, penv);
+
+		this->begin_txn();
+		// This transaction will prevent push_back to autocommit,
+		// as expected, because a single push_back should not be
+		// automatic in this function
+		//
+		try {
+			for (i = 0; i < n; i++)
+				push_back(val);
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+		this->commit_txn();
+	}
+
+	/// \brief Copy constructor.
+	///
+	/// This function supports auto-commit. 
+	/// Insert all elements in x into this container.
+	/// \sa db_container(const db_container&)
+	db_vector(const self& x) : db_container(x)
+	{
+		// This objects underlying db should have been opened already,
+		// only copy db contents.
+		//
+		verify_db_handles(x);
+		this->set_db_handle_int(this->clone_db_config(
+		    x.get_db_handle()), x.get_db_env_handle());
+
+		this->begin_txn();
+
+		try {
+			copydb(x);
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+		this->commit_txn();
+	}
+
+	/// Range constructor.
+	/// This function supports auto-commit. 
+	// The order of parameters has to be altered in order to avoid
+	// clashing with the other constuctor above (the one with size_type
+	// as first parameter).
+	/// Insert a range of elements into this container. The range is 
+	/// [first, last), which contains elements that can be converted to 
+	/// type T automatically.
+	/// See class detail for handle requirement.
+	/// \param dbp The same as that of db_container(Db*, DbEnv*);
+	/// \param penv The same as that of db_container(Db*, DbEnv*);
+	/// \param first Range closed boundary.
+	/// \param last Range open boundary.
+	/// \sa db_vector(Db*, DbEnv*);
+	template <class InputIterator>
+	db_vector(Db*dbp, DbEnv *penv,
+	    InputIterator first, InputIterator last) : base(dbp, penv)
+	{
+		const char *errmsg;
+
+		this->open_db_handles(dbp, penv, DB_RECNO, DB_CREATE |
+		    DB_THREAD, DB_RENUMBER);
+		if ((errmsg = verify_config(dbp, penv)) != NULL)
+			THROW(InvalidArgumentException, ("Db*", errmsg));
+
+		this->set_db_handle_int(dbp, penv);
+
+		this->begin_txn();
+		try {
+			push_range(first, last);
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+
+		this->commit_txn();
+	}
+
+	/// Range constructor.
+	/// This function supports auto-commit. 
+	/// Insert the range of elements in [first, last) into this container.
+	/// See class detail for handle requirement.
+	/// \param dbp The same as that of db_container(Db*, DbEnv*);
+	/// \param penv The same as that of db_container(Db*, DbEnv*);
+	/// \param first Range closed boundary.
+	/// \param last Range open boundary.
+	/// \sa db_vector(Db*, DbEnv*);
+	db_vector(const_iterator first, const_iterator last,
+	    Db*dbp = NULL, DbEnv *penv = NULL) : base(dbp, penv)
+	{
+		const char *errmsg;
+
+		this->open_db_handles(dbp, penv, DB_RECNO, DB_CREATE |
+		    DB_THREAD, DB_RENUMBER);
+		if ((errmsg = verify_config(dbp, penv)) != NULL)
+			THROW(InvalidArgumentException, ("Db*", errmsg));
+		this->set_db_handle_int(dbp, penv);
+
+		this->begin_txn();
+		try {
+			push_range(first, last);
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+
+		this->commit_txn();
+	}
+
+	// We don't have to close Berkeley DB database or environment handles
+	// because all related handles are managed by ResourceManager and 
+	// closed in the right order when the program exits.
+	//
+	virtual ~db_vector() {
+	}
+
+	////////////////////////////////////////////////////////////////////
+
+	/// \brief Container assignment operator.
+	///
+	/// This function supports auto-commit. 
+	/// This db_vector is assumed to be valid for use, only copy
+	/// content of x into this container.
+	/// \param x The right value container.
+	/// \return The container x's reference.
+	const self& operator=(const self& x)
+	{
+		ASSIGNMENT_PREDCOND(x)
+		// TODO: rename verify_db_handles to validate_db_handle
+		db_container::operator =(x);
+		verify_db_handles(x);
+		this->begin_txn();
+		try {
+			copydb(x);
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+
+		this->commit_txn();
+		return x;
+	}
+
+	////////////////////////////////////////////////////////////////////
+	//
+	// Begin db_vector comparison functions.
+	/// \name Compare functions.
+	/// \sa http://www.sgi.com/tech/stl/Vector.html
+	//@{ 
+	/// \brief Container equality comparison operator.
+	///
+	/// This function supports auto-commit. 
+	/// \return Compare two vectors, return true if they have identical
+	/// sequences of elements, otherwise return false.
+	/// \param v2 The vector to compare against.
+	template <Typename T2, Typename T3>
+	bool operator==(const db_vector<T2, T3>& v2) const
+	{
+		bool ret;
+		size_t sz;
+
+		verify_db_handles(v2);
+		typename self::iterator i1;
+		typename db_vector<T2, T3>::iterator i2;
+
+		try {
+			this->begin_txn();
+			if ((sz = this->size()) != v2.size()) {
+				ret = false;
+				this->commit_txn();
+				return ret;
+			}
+			if (sz == 0) {
+				ret = true;
+				this->commit_txn();
+				return ret;
+			}
+
+			// Identical size, compare each element.
+			for (i1 = begin(), i2 = v2.begin(); i1 != end() &&
+			    i2 != v2.end(); ++i1, ++i2)
+				if (!((T)(*i1) == (T2)(*i2))) {
+					ret = false;
+					this->commit_txn();
+					return ret;
+				}
+
+			// All elements equal, the two vectors are equal.
+			ret = true;
+			this->commit_txn();
+			return ret;
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+	}
+
+	/// \brief Container in-equality comparison operator.
+	///
+	/// This function supports auto-commit. 
+	/// \param v2 The vector to compare against.
+	/// \return Returns false if elements in each slot of both 
+	/// containers equal; Returns true otherwise.
+	template <Typename T2, Typename T3>
+	bool operator!=(const db_vector<T2, T3>& v2) const
+	{
+		return !this->operator==(v2);
+	}
+
+	/// \brief Container equality comparison operator.
+	///
+	/// This function supports auto-commit. 
+	/// \return Compare two vectors, return true if they have identical 
+	/// elements, otherwise return false.
+	bool operator==(const self& v2) const
+	{
+		bool ret;
+
+		COMPARE_CHECK(v2)
+		verify_db_handles(v2);
+
+		try {
+			this->begin_txn();
+			if (this->size() != v2.size()) {
+				ret = false;
+				this->commit_txn();
+				return ret;
+			}
+			typename self::const_iterator i1;
+			typename self::const_iterator i2;
+			// Identical size, compare each element.
+			for (i1 = begin(), i2 = v2.begin(); i1 != end() &&
+			    i2 != v2.end(); ++i1, ++i2)
+				if (!(*i1 == *i2)) {
+					ret = false;
+					this->commit_txn();
+					return ret;
+				}
+
+			// All elements are equal, the two vectors are equal.
+			ret = true;
+			this->commit_txn();
+			return ret;
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+	}
+
+	/// \brief Container in-equality comparison operator.
+	///
+	/// This function supports auto-commit. 
+	/// \param v2 The vector to compare against.
+	/// \return Returns false if elements in each slot of both 
+	/// containers equal; Returns true otherwise.
+	bool operator!=(const self& v2) const
+	{
+		return !this->operator==(v2);
+	}
+
+	/// \brief Container less than comparison operator.
+	///
+	/// This function supports auto-commit. 
+	/// \param v2 The container to compare against.
+	/// \return Compare two vectors, return true if this is less 
+	/// than v2, otherwise return false.
+	bool operator<(const self& v2) const
+	{
+		bool ret;
+
+		if (this == &v2)
+			return false;
+
+		verify_db_handles(v2);
+		typename self::const_iterator i1;
+		typename self::const_iterator i2;
+		size_t s1, s2, sz, i;
+
+		try {
+			this->begin_txn();
+			s1 = this->size();
+			s2 = v2.size();
+			sz = s1 < s2 ? s1 : s2;
+
+			// Compare each element.
+			for (i1 = begin(), i = 0, i2 = v2.begin();
+			    i < sz;
+			    ++i1, ++i2, ++i) {
+				if (*i1 == *i2)
+					continue;
+				else {
+					if (*i1 < *i2)
+						ret = true;
+					else
+						ret = false;
+					this->commit_txn();
+					return ret;
+				}
+			}
+
+			ret = s1 < s2;
+			this->commit_txn();
+			return ret;
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+	}
+	//@} // cmp_funcs
+	////////////////////////////////////////////////////////////////////
+
+	/// \brief Resize this container to specified size n, insert values t
+	/// if need to enlarge the container.
+	///
+	/// This function supports auto-commit. 
+	/// \param n The number of elements in this container after the call.
+	/// \param t The value to insert when enlarging the container. 
+	/// \sa http://www.cplusplus.com/reference/stl/vector/resize.html
+	inline void resize(size_type n, T t = T())
+	{
+		size_t i, sz;
+
+		try {
+			begin_txn();
+			if (n == (sz = size())) {
+				commit_txn();
+				return;
+			}
+
+			if (n < sz) // Remove sz - n elements at tail.
+				erase(begin() + n, end());
+			else
+				for (i = sz; i < n; i++)
+					push_back(t);
+			commit_txn();
+		} catch (...) {
+			abort_txn();
+			throw;
+		}
+	}
+
+	/// \brief Reserve space.
+	///
+	/// The vector is backed by Berkeley DB, we always have enough space.
+	/// This function does nothing, because dbstl does not have to manage
+	/// memory space.
+	inline void reserve(size_type /* n */)
+	{
+	}
+
+	/** \name Assign functions
+	See the function documentation for the correct usage of b_truncate 
+	parameter.
+	@{
+	The following four member functions have default parameter b_truncate,
+	because they require all key/data pairs in the database be deleted 
+	before the real operation, and by default we use Db::truncate to 
+	truncate the database rather than delete the key/data pairs one by
+	one, but Db::truncate requirs no open cursors on the database handle,
+	and the four member functions will close any open cursors of backing 
+	database handle in current thread, but can do nothing to cursors of 
+	other threads opened from the same database handle. 
+	So you must make sure there are no open cursors of the database handle
+	in any other threads. On the other hand, users can specify "false" to
+	the b_truncate parameter and thus the key/data pairs will be deleted
+	one by one. Other than that, they have identical behaviors as their 
+	counterparts in std::vector. 
+	\sa http://www.cplusplus.com/reference/stl/vector/assign.html
+	*/
+	/// Assign a range [first, last) to this container.
+	/// \param first The range closed boundary.
+	/// \param last The range open boundary.
+	/// \param b_truncate See its member group doc for details.
+	template <class InputIterator>
+	void assign ( InputIterator first, InputIterator last, 
+	    bool b_truncate = true)
+	{
+		if (this->get_db_handle() == NULL)
+			return;
+
+		this->begin_txn();
+		try {
+			clear(b_truncate);
+			push_range(first, last);
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+		this->commit_txn();
+	}
+
+	/// Assign a range [first, last) to this container.
+	/// \param first The range closed boundary.
+	/// \param last The range open boundary.
+	/// \param b_truncate See its member group doc for details.
+	void assign(const_iterator first, const_iterator last, 
+	    bool b_truncate = true)
+	{
+		if (this->get_db_handle() == NULL)
+			return;
+
+		this->begin_txn();
+		try {
+			clear(b_truncate);
+			push_range(first, last);
+
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+		this->commit_txn();
+	}
+
+	/// Assign n number of elements of value u into this container.
+	/// \param n The number of elements in this container after the call.
+	/// \param u The value of elements to insert.
+	/// \param b_truncate See its member group doc for details.
+	/// This function supports auto-commit. 
+	void assign ( size_type n, const T& u, bool b_truncate = true)
+	{
+		if (this->get_db_handle() == NULL)
+			return;
+
+		this->begin_txn();
+		try {
+			clear(b_truncate);
+			size_t i;
+			for (i = 0; i < n; i++)
+				push_back(u);
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+
+		this->commit_txn();
+	}
+	//@} // assign_funcs
+
+	// Directly use DB->put, so that when there is no explicit transaction,
+	// it is autocommit. This
+	// method is often called by other db_vector methods, in that case
+	// those methods will begin/commit_txn internally, causing push_back
+	// to not autocommit, as expected.
+	/// \brief Push back an element into the vector.
+	///
+	/// This function supports auto-commit. 
+	/// \param x The value of element to push into this vector.
+	/// \sa http://www.cplusplus.com/reference/stl/vector/push_back.html
+	inline void push_back ( const T& x )
+	{
+		index_type k0 = 0; // This value is ignored.
+		int ret;
+
+		// x may be an temporary object, so must copy it.
+		DataItem dt(x, false), k(k0, true);
+		// In CDS mode, the current transaction is the DB_TXN created
+		// by cds_group_begin.
+		BDBOP(this->get_db_handle()->put(ResourceManager::instance()->
+		    current_txn(this->get_db_env_handle()),
+		    &(k.get_dbt()), &(dt.get_dbt()), DB_APPEND), ret);
+	}
+
+	/// \brief Pop out last element from the vector.
+	///
+	/// This function supports auto-commit. 
+	/// \sa http://www.cplusplus.com/reference/stl/vector/pop_back.html
+	void pop_back ()
+	{
+		try {
+			iterator derefitr;
+
+			this->begin_txn();
+			init_itr(derefitr);
+			open_itr(derefitr);
+			derefitr.last();
+			derefitr.pcsr_->del();
+			this->commit_txn();
+		} catch(...) {
+			this->abort_txn();
+			throw;
+		}
+	}
+
+	////////////////////////////////////////////////////////////////////
+	//
+	// Begin std::deque and std::list specific public functions.
+	//
+	// These methods are not in std::vector, but are in std::list and
+	// std::deque. They are defined here so that db_vector can be used to
+	// replace std::list and std::deque.
+	/// \name Functions specific to deque and list
+	/// These functions come from std::list and std::deque, and have
+	/// identical behaviors to their counterparts in std::list/std::deque.
+	/// \sa http://www.cplusplus.com/reference/stl/deque/pop_front.html 
+	/// http://www.cplusplus.com/reference/stl/deque/push_front.html
+	//@{
+	/// \brief Push an element x into the vector from front.
+	/// \param x The element to push into this vector.
+	/// This function supports auto-commit. 
+	void push_front (const T& x)
+	{
+		int flag, ret;
+
+		try {
+			this->begin_txn();
+			iterator derefitr;
+			init_itr(derefitr);
+			open_itr(derefitr);
+			// MOVE iterator and cursor to 1st element.
+			ret = derefitr.first();
+			if (ret < 0)
+				flag = DB_KEYLAST; // empty
+			else
+				flag = DB_BEFORE;
+			derefitr.pcsr_->insert(x, flag);
+			this->commit_txn();
+		} catch(...) {
+			this->abort_txn();
+			throw;
+		}
+	}
+
+	/// \brief Pop out the front element from the vector.
+	///
+	/// This function supports auto-commit. 
+	void pop_front ()
+	{
+		try {
+			this->begin_txn();
+			iterator derefitr;
+			init_itr(derefitr);
+			open_itr(derefitr);
+			derefitr.first();
+			derefitr.pcsr_->del();
+			this->commit_txn();
+		} catch(...) {
+			this->abort_txn();
+			throw;
+		}
+
+	}
+	//@}
+	////////////////////////////////////////////////////////////////////
+
+	////////////////////////////////////////////////////////////////////
+	//
+	// Begin insert and erase functions.
+	//
+	// This method can not be autocommit because pos can not be reopened
+	// while it already points to a dest position. In order to gain
+	// transaction it should have already been opened in a transactional
+	// context, so it is meaningless to wrap the insert operation with
+	// begin/commit transaction in this method.
+	/// \name Insert functions
+	/// The iterator pos in the functions must be a read-write iterator,
+	/// can't be read only.
+	/// \sa http://www.cplusplus.com/reference/stl/vector/insert.html
+	//@{
+	/// \brief Insert x before position pos.
+	/// \param x The element to insert.
+	/// \param pos The position before which to insert. 
+	iterator insert (iterator pos, const T& x)
+	{
+		u_int32_t flag;
+		bool isempty;
+
+		make_insert_args(pos, flag, isempty);
+
+		pos.pcsr_->insert(x, flag);
+		pos.update_cur_pair(); // Sync with underlying cursor.
+
+		return pos; // Returns the new position's iterator.
+	}
+
+	/// \brief Insert n number of elements x before position pos.
+	/// \param x The element to insert.
+	/// \param pos The position before which to insert. 
+	/// \param n The number of elements to insert.
+	void insert (iterator pos, size_type n, const T& x)
+	{
+		u_int32_t flag;
+		size_t i;
+		bool isempty;
+
+		make_insert_args(pos, flag, isempty);
+
+		for (i = 0; i < n; i++) {
+			pos.pcsr_->insert(x, flag);
+			pos.update_cur_pair();
+			// Move the underlying Dbc*cursor to next record
+			// (i.e. the orig record it pointed to before
+			// the insertion). So it will point to
+			// the new record after insertion.
+			//
+			if (flag == DB_BEFORE)
+				++pos;
+
+			// If using DB_AFTER flag, no need to move because
+			// cursor already points to the newly inserted record
+			// after the orig record it pointed to.
+			//
+
+			// There is already data in the underlying database
+			// so use DB_BEFORE unless pos is begin() and the
+			// vector was empty before this insert call.
+			//
+			if (flag == DB_KEYLAST) {
+				if(isempty)
+					flag = DB_AFTER;
+				else
+			 // This branch can never be reached because any
+			 // iterator of a empty container can only have its
+			 // cursor at the begin() position.
+			 //
+					flag = DB_BEFORE;
+			}
+		}
+	}
+
+	/// \brief Range insertion.
+	///
+	/// Insert elements in range [first, last) into this vector before
+	/// position pos.
+	/// \param first The closed boundary of the range.
+	/// \param last The open boundary of the range.
+	/// \param pos The position before which to insert. 
+	template <class InputIterator>
+	void insert (iterator pos, InputIterator first, InputIterator last)
+	{
+		u_int32_t flag;
+		InputIterator itr;
+		bool isempty;
+
+		make_insert_args(pos, flag, isempty);
+		// !!!XXX
+		// The cursor will point to the newly inserted record, so we
+		// need to move the cursor to the original one.
+		//
+
+		for (itr = first; itr != last; ++itr) {
+			pos.pcsr_->insert(*itr, flag);
+			pos.update_cur_pair();
+			// Move the underlying Dbc*cursor to next record
+			// (i.e. the orig record it pointed to before
+			// the insertion). So it will point to
+			// the new record after insertion.
+			//
+			if (flag == DB_BEFORE)
+				++pos;
+			// There is already data in the underlying database
+			// so use DB_BEFORE unless pos is begin() and the
+			// vector was empty before this insert call.
+			//
+			if (flag == DB_KEYLAST) {
+				// pos == begin() && this was empty
+				if(isempty)
+					flag = DB_AFTER;
+				else
+			 // This branch can never be reached because any
+			 // iterator of a empty container can only have its
+			 // cursor at the begin() position.
+			 //
+					flag = DB_BEFORE;
+			}
+		}
+	}
+
+	// this method can not be autocommitted, reason as above
+	/// \brief Range insertion.
+	///
+	/// Insert elements in range [first, last) into this vector before
+	/// position pos.
+	/// \param first The closed boundary of the range.
+	/// \param last The open boundary of the range.
+	/// \param pos The position before which to insert. 
+	void insert (iterator pos, const_iterator first, const_iterator last)
+	{
+		u_int32_t flag;
+		iterator itr;
+		bool isempty;
+
+		make_insert_args(pos, flag, isempty);
+
+		for (itr = first; itr != last; ++itr) {
+			pos.pcsr_->insert(*itr, flag);
+			pos.update_cur_pair();
+			// Move the underlying Dbc*cursor to next record
+			// (i.e. the orig record it pointed to before
+			// the insertion). So it will point to
+			// the new record after insertion.
+			//
+			if (flag == DB_BEFORE)
+				++pos;
+			// There is already data in the underlying database
+			// so use DB_BEFORE unless pos is begin() and the
+			// vector was empty before this insert call.
+			//
+			if (flag == DB_KEYLAST) {
+				// pos == begin() && this was empty.
+				if(isempty)
+					flag = DB_AFTER;
+				else
+					flag = DB_BEFORE;
+			}
+		}
+	}
+	//@}
+
+	/// \name Erase functions
+	/// The iterator pos in the functions must be a read-write iterator,
+	/// can't be read only.
+	/// \sa http://www.cplusplus.com/reference/stl/vector/erase.html
+	//@{
+	/// \brief Erase element at position pos.
+	/// \param pos The valid position in the container's range to erase.
+	/// \return The next position after the erased element.
+	inline iterator erase (iterator pos)
+	{
+		if (pos == end_itr_)
+			return pos;
+		pos.pcsr_->del();
+		++pos;
+		// Synchronized with underlying cursor.
+		return pos;
+	}
+
+	/// \brief Erase elements in range [first, last)
+	/// \param first The closed boundary of the range.
+	/// \param last The open boundary of the range.
+	/// \return The next position after the erased elements.
+	iterator erase (iterator first, iterator last)
+	{
+		iterator itr;
+		int ret = 0;
+		Dbt k, d;
+
+		// If ret is non-zero, it is because there is no element in
+		// this container any more.
+		//
+		for (itr = first; itr != last && ret == 0; ++itr) {
+			if (itr == end_itr_)
+				return itr;
+			ret = itr.pcsr_->del();
+		}
+		return itr;
+	}
+	//@}
+	////////////////////////////////////////////////////////////////////
+
+	/// \brief Swap content with another vector vec.
+	/// \param vec The other vector to swap content with.
+	/// This function supports auto-commit. 
+	/// \sa http://www.cplusplus.com/reference/stl/vector/swap.html
+	void swap (self& vec)
+	{
+		T tmp;
+		size_t sz, vsz, i, j, m;
+		self& me = *this;
+		self *longer, *shorter;
+
+		verify_db_handles(vec);
+		this->begin_txn();
+		try {
+			sz = this->size();
+			vsz = vec.size();
+			// do swap
+			for (i = 0; (i < sz) && (i < vsz); i++) {
+				tmp = me[(index_type)i];
+				me[(index_type)i] = vec[(index_type)i];
+				vec[(index_type)i] = tmp;
+			}
+
+			// Move the longer vector's remaining part to the
+			// shorter one.
+			//
+			if (sz == vsz)
+				return;
+			else if (sz < vsz) {
+				longer = &vec;
+				shorter = &me;
+				j = vsz;
+			} else {
+				longer = &me;
+				shorter = &vec;
+				j = sz;
+			}
+
+			self &lv = *longer;
+			self &sv = *shorter;
+			m = i;
+			for (; i < j; i++)
+				sv.push_back(lv[(index_type)i]);
+
+			typename self::iterator itr1 = 
+			    lv.begin() + (int)m, itr2 = lv.end();
+
+			lv.erase(itr1, itr2);
+		} catch (...) {
+			this->abort_txn();
+			throw;
+		}
+		this->commit_txn();
+	}
+
+	// When DB_AUTO_COMMIT is set, no transaction needs to be begun to
+	// support autocommit because DB->truncate internally supports it.
+	/// Remove all elements of the vector, make it an empty vector.
+	/// This function supports auto-commit. 
+	/// \param b_truncate Same as that of db_vector::assign().
+	/// \sa http://www.cplusplus.com/reference/stl/vector/clear.html
+	void clear(bool b_truncate = true)
+	{
+		int ret;
+		u_int32_t flag;
+		DbEnv *penv = this->get_db_handle()->get_env();
+
+		if (b_truncate) {
+			ResourceManager::instance()->close_db_cursors(
+			    this->get_db_handle());
+
+			BDBOP2(this->get_db_handle()->truncate(
+			    ResourceManager::instance()->current_txn(penv),
+			    NULL, 0), ret, this->abort_txn());
+		} else {
+			ReadModifyWriteOption brmw(
+			    ReadModifyWriteOption::no_read_modify_write());
+
+			BDBOP(penv->get_open_flags(&flag), ret);
+
+			// DB_RMW flag requires locking subsystem.
+			if ((flag & DB_INIT_LOCK) || (flag & DB_INIT_CDB) ||
+			    (flag & DB_INIT_TXN))
+				brmw = 
+				    ReadModifyWriteOption::read_modify_write();
+
+			try { // Truncate is capable of autocommit internally.
+				this->begin_txn();
+				erase(begin(brmw, false), end());
+				this->commit_txn();
+			} catch (...) {
+				this->abort_txn();
+				throw;
+			}
+		}
+	}
+
+	////////////////////////////////////////////////////////////////////
+	//
+	// Begin methods only defined in std::list class.
+	/// \name std::list specific functions
+	/// \sa http://www.cplusplus.com/reference/stl/list/
+	//@{
+	/// \brief Remove all elements whose values are "value" from the list.
+	///
+	/// This function supports auto-commit. 
+	/// \param value The target value to remove.
+	/// \sa http://www.cplusplus.com/reference/stl/list/remove/
+	void remove(const T& value)
+	{
+		iterator i;
+
+		try {
+			begin_txn();
+			for (i = begin(); i != end(); ++i)
+				if (*i == value)
+					erase(i);
+			commit_txn();
+		} catch (...) {
+			abort_txn();
+			throw;
+		}
+	}
+
+	/// \brief Remove all elements making "pred" return true.
+	///
+	/// This function supports auto-commit. 
+	/// \param pred The binary predicate judging elements in this list.
+	/// \sa http://www.cplusplus.com/reference/stl/list/remove_if/
+	template <class Predicate>
+	void remove_if(Predicate pred)
+	{
+		iterator i;
+
+		try {
+			begin_txn();
+			for (i = begin(); i != end(); ++i)
+				if (pred(*i))
+					erase(i);
+			commit_txn();
+		} catch (...) {
+			abort_txn();
+			throw;
+		}
+	}
+
+	/// \brief Merge content with another container.
+	///
+	/// This function supports auto-commit. 
+	/// \param x The other list to merge with.
+	/// \sa http://www.cplusplus.com/reference/stl/list/merge/
+	void merge(self& x)
+	{
+		DbstlListSpecialOps<T, value_type_sub> obj(this);
+		obj.merge(x);
+	}
+
+	
+	/// \brief Merge content with another container.
+	///
+	/// This function supports auto-commit. 
+	/// \param x The other list to merge with.
+	/// \param comp The compare function to determine insertion position.
+	/// \sa http://www.cplusplus.com/reference/stl/list/merge/
+	template <class Compare>
+	void merge(self& x, Compare comp)
+	{
+		verify_db_handles(x);
+		iterator itr, itrx;
+
+		try {
+			begin_txn();
+			for (itr = begin(), itrx = x.begin();
+			    itr != end_itr_ && itrx != x.end();) {
+				if (!comp(*itr, *itrx)) {
+					insert(itr, *itrx);
+					++itrx;
+				} else
+					++itr;
+			}
+			if (itr == end_itr_ && itrx != x.end())
+				insert(itr, itrx, x.end());
+			x.clear();
+			commit_txn();
+		} catch (...) {
+			abort_txn();
+			throw;
+		}
+	}
+
+	/// \brief Remove consecutive duplicate values from this list.
+	///
+	/// This function supports auto-commit. 
+	/// \sa http://www.cplusplus.com/reference/stl/list/unique/
+	void unique()
+	{
+		DbstlListSpecialOps<T, value_type_sub> obj(this);
+		obj.unique();
+	}
+
+	/// \brief Remove consecutive duplicate values from this list.
+	///
+	/// This function supports auto-commit. 
+	/// \param binary_pred The compare predicate to dertermine uniqueness.
+	/// \sa http://www.cplusplus.com/reference/stl/list/unique/
+	template <class BinaryPredicate>
+	void unique(BinaryPredicate binary_pred)
+	{
+		DbstlListSpecialOps<T, value_type_sub> obj(this);
+		obj.unique(binary_pred);
+	}
+
+	/// \brief Sort this list.
+	///
+	/// This function supports auto-commit. 
+	/// \sa http://www.cplusplus.com/reference/stl/list/sort/
+	void sort()
+	{
+		DbstlListSpecialOps<T, value_type_sub> obj(this);
+		obj.sort();
+	}
+
+	/// \brief Sort this list.
+	///
+	/// This function supports auto-commit. 
+	/// \param comp The compare operator to determine element order.
+	/// \sa http://www.cplusplus.com/reference/stl/list/sort/
+	template <class Compare>
+	void sort(Compare comp)
+	{
+		DbstlListSpecialOps<T, value_type_sub> obj(this);
+		obj.sort(comp);
+	}
+
+	/// \brief Reverse this list.
+	///
+	/// This function supports auto-commit. 
+	/// \sa http://www.cplusplus.com/reference/stl/list/reverse/
+	void reverse()
+	{
+		try {
+			self tmp;
+			const self &cthis = *this;
+			const_reverse_iterator ri;
+
+			begin_txn();
+			for (ri = cthis.rbegin(BulkRetrievalOption::
+			    bulk_retrieval()); ri != rend(); ++ri)
+				tmp.push_back(*ri);
+			assign(tmp.begin(), tmp.end());
+			commit_txn();
+		} catch (...) {
+			abort_txn();
+			throw;
+		}
+	}
+
+	/// \brief Moves elements from list x into this list.
+	///
+	/// Moves all elements in list x into this list 
+	/// container at the 
+	/// specified position, effectively inserting the specified 
+	/// elements into the container and removing them from x.
+	/// This function supports auto-commit. 
+	/// \param position Position within the container where the elements 
+	/// of x are inserted.
+	/// \param x The other list container to splice from.
+	/// \sa http://www.cplusplus.com/reference/stl/list/splice/
+	void splice (iterator position, self& x)
+	{
+		verify_db_handles(x);
+		try {
+			begin_txn();
+			insert(position, x.begin(), x.end());
+			x.clear();
+			commit_txn();
+		} catch (...) {
+			abort_txn();
+			throw;
+		}
+	}
+
+	/// \brief Moves elements from list x into this list.
+	///
+	/// Moves elements at position i of list x into this list 
+	/// container at the 
+	/// specified position, effectively inserting the specified 
+	/// elements into the container and removing them from x.
+	/// This function supports auto-commit. 
+	/// \param position Position within the container where the elements 
+	/// of x are inserted.
+	/// \param x The other list container to splice from.
+	/// \param i The position of element in x to move into this list.
+	/// \sa http://www.cplusplus.com/reference/stl/list/splice/
+	void splice (iterator position, self& x, iterator i)
+	{
+		verify_db_handles(x);
+		try {
+			begin_txn();
+			assert(!(i == x.end()));
+			insert(position, *i);
+			x.erase(i);
+			commit_txn();
+		} catch (...) {
+			abort_txn();
+			throw;
+		}
+	}
+
+	/// \brief Moves elements from list x into this list.
+	///
+	/// Moves elements in range [first, last) of list x into this list 
+	/// container at the 
+	/// specified position, effectively inserting the specified 
+	/// elements into the container and removing them from x.
+	/// This function supports auto-commit. 
+	/// \param position Position within the container where the elements 
+	/// of x are inserted.
+	/// \param x The other list container to splice from.
+	/// \param first The range's closed boundary.
+	/// \param last The range's open boundary.
+	/// \sa http://www.cplusplus.com/reference/stl/list/splice/
+	void splice (iterator position, self& x, iterator first, iterator last)
+	{
+		verify_db_handles(x);
+		try {
+			begin_txn();
+			insert(position, first, last);
+			x.erase(first, last);
+			commit_txn();
+		} catch (...) {
+			abort_txn();
+			throw;
+		}
+	}
+	//@}
+	////////////////////////////////////////////////////////////////////
+
+private:
+	typedef db_vector_iterator<T, value_type_sub> iterator_type;
+	typedef db_container base;
+	friend class db_vector_iterator<T, value_type_sub>;
+	friend class db_vector_base_iterator<T>;
+	friend class db_reverse_iterator<iterator, const_iterator>;
+	friend class db_reverse_iterator<const_iterator, iterator>;
+	friend class DbstlListSpecialOps<T, value_type_sub>;
+
+	// Replace current contents with those in 'x'.
+	inline void copydb(const self&x)
+	{
+		const_iterator itr;
+
+		// TODO: Make sure clear can succeed, it fails if there are
+		// cursors open in other threads.
+		clear(false);
+		for (itr = x.begin(); itr != x.end(); ++itr)
+			push_back(*itr);
+	}
+
+	static iterator end_itr_;
+
+	template <Typename InputIterator>
+	inline void push_range(InputIterator& first, InputIterator& last)
+	{
+		InputIterator itr;
+
+		for (itr = first; itr != last; ++itr)
+			push_back(*itr);
+	}
+
+	inline void push_range(const_iterator& first, const_iterator& last)
+	{
+		const_iterator itr;
+
+		for (itr = first; itr != last; ++itr)
+			push_back(*itr);
+
+	}
+
+	// Move pos to last, pos must initially be the end() iterator.
+	inline void end_to_last(const const_iterator& pos) const
+	{
+		if (pos != end_itr_)
+			return;
+		pos.pcsr_.set_cursor(new TRandDbCursor());
+		open_itr(pos);
+		pos.last();
+	}
+
+	// This function generate appropriate flags for cursor insert calls.
+	void make_insert_args(iterator& pos, u_int32_t& flag, bool &isempty)
+	{
+		isempty = false;					
+		if (pos.itr_status_ == INVALID_ITERATOR_POSITION) {	
+			((self*)pos.owner_)->end_to_last(pos);		
+			/* Empty db, iterator at "begin()". */		
+			if (((self*)pos.owner_)->empty()) {		
+				flag = DB_KEYLAST; /* Empty */		
+				isempty = true;				
+			} else 	
+				/* Move pos to last element. */
+				flag = DB_AFTER;
+		} else							
+			flag = DB_BEFORE; 
+	}
+
+	// Open iterator and move it to point the 1st key/data pair.
+	//
+	void open_itr(const const_iterator&itr, bool readonly = false) const
+	{
+		u_int32_t oflags = 0;
+		int ret;
+		DbEnv *penv = this->get_db_handle()->get_env();
+
+		itr.owner_ = (db_container*)this;
+		if (!readonly && penv != NULL) {
+			BDBOP((penv->get_open_flags(&oflags)), ret);
+			// Open a writeable cursor when in CDS mode and not
+			// requesting a read only iterator.
+			if ((oflags & DB_INIT_CDB) != 0)
+				((self *)this)->set_cursor_open_flags(
+				    this->get_cursor_open_flags() |
+				    DB_WRITECURSOR);
+		}
+		if (!itr.pcsr_)
+			itr.pcsr_.set_cursor(new TRandDbCursor(
+			    itr.bulk_retrieval_, 
+			    itr.rmw_csr_, itr.directdb_get_));
+		itr.itr_status_ = itr.pcsr_->open((db_container*)this,
+		    this->get_cursor_open_flags());
+	}
+
+	void open_itr(const reverse_iterator &itr, bool readonly = false) const
+	{
+		u_int32_t oflags = 0;
+		int ret;
+		DbEnv *penv = this->get_db_handle()->get_env();
+
+		itr.owner_ = (db_container*)this;
+		if (!readonly && penv != NULL) {
+			BDBOP((penv->get_open_flags(&oflags)) , ret);
+			// Open a writeable cursor when in CDS mode and not
+			// requesting a read only iterator.
+			if ((oflags & DB_INIT_CDB) != 0)
+				((self *)this)->set_cursor_open_flags(
+				    this->get_cursor_open_flags() |
+				    DB_WRITECURSOR);
+		}
+		if (!itr.pcsr_)
+			itr.pcsr_.set_cursor(new TRandDbCursor(
+			    itr.bulk_retrieval_,
+			    itr.rmw_csr_, itr.directdb_get_));
+		itr.itr_status_ = itr.pcsr_->open((db_container*)this,
+		    this->get_cursor_open_flags());
+		itr.update_cur_pair();
+	}
+
+	inline void init_itr(const_iterator &itr) const
+	{
+		itr.owner_ = (db_container*)this;
+	}
+
+	// Certain flags and parameters need to be set to the database and 
+	// environment handle for them to back-up a certain type of container.
+	// This function verifies that db and env handles are well configured 
+	// to be suitable for this type of containers.
+	virtual const char* verify_config(Db*db, DbEnv*env) const
+	{
+		u_int32_t oflags, sflags, oflags2;
+		const char *errmsg = NULL;
+		int ret;
+		DBTYPE dbtype;
+
+		errmsg = db_container::verify_config(db, env);
+		if (errmsg)
+			return errmsg;
+
+		oflags = sflags = oflags2 = 0;
+		BDBOP((db->get_type(&dbtype)) || (db->get_open_flags(&oflags))
+		     || (db->get_flags(&sflags)) ||
+		     (env->get_open_flags(&oflags2)), ret);
+
+		if (dbtype != DB_RECNO)
+			errmsg = "Must use DB_RECNO type of database.";
+		// DB_THREAD is not always required, only required if the db 
+		// handle is shared among multiple threads, which is not a 
+		// case we can detect here.
+
+		return errmsg;
+	}
+
+
+}; // db_vector
+
+template <Typename T, Typename value_type_sub>
+typename db_vector<T, value_type_sub>::iterator
+    db_vector<T, value_type_sub>::end_itr_;
+
+// Partial spececialization version of std::swap for db_vector.
+template <Typename T, Typename value_type_sub>
+void swap(db_vector<T, value_type_sub>&v1, db_vector<T, value_type_sub>&v2)
+{
+	v1.swap(v2);
+}
+
+
+
+template <typename T, typename T2>
+class _exported DbstlListSpecialOps
+{
+	typedef db_vector<T, T2> partner;
+	typedef typename partner::iterator iterator;
+	partner *that;
+public:
+	DbstlListSpecialOps(partner *that1)
+	{
+		that = that1;
+	}
+
+	template <class BinaryPredicate>
+	void unique(BinaryPredicate binary_pred)
+	{
+		T t, t2;
+
+		try {
+			that->begin_txn();
+			iterator i = that->begin();
+			t2 = *i;
+			++i;
+			for (; i != that->end_itr_; ++i) {
+				if (binary_pred((t = *i), t2))
+					that->erase(i);
+				else
+					t2 = t;
+			}
+			that->commit_txn();
+		} catch (...) {
+			that->abort_txn();
+			throw;
+		}
+	}
+
+	void unique()
+	{
+		T t, t2;
+
+		try {
+			that->begin_txn();
+			iterator i = that->begin();
+			t2 = *i;
+			++i;
+			for (; i != that->end_itr_; ++i) {
+				if ((t = *i) == t2)
+					that->erase(i);
+				else
+					t2 = t;
+			}
+			that->commit_txn();
+		} catch (...) {
+			that->abort_txn();
+			throw;
+		}
+	}
+
+	/// This function supports auto-commit. 
+	void merge(partner& x)
+	{
+		that->verify_db_handles(x);
+		T b;
+		iterator itr, itrx;
+
+		try {
+			that->begin_txn();
+			for (itr = that->begin(), itrx = x.begin();
+			    itr != that->end_itr_ && itrx != x.end();) {
+				if (*itr > (b = *itrx)) {
+					that->insert(itr, b);
+					++itrx;
+				} else
+					++itr;
+			}
+			if (itr == that->end_itr_ && itrx != x.end())
+				that->insert(itr, itrx, x.end());
+			x.clear();
+			that->commit_txn();
+		} catch (...) {
+			that->abort_txn();
+			throw;
+		}
+	}
+
+	/// This function supports auto-commit. 
+	void sort()
+	{
+		try {
+			that->begin_txn();
+			std::sort(that->begin(), that->end());
+			that->commit_txn();
+		} catch (...) {
+			that->abort_txn();
+			throw;
+		}
+	}
+
+	/// This function supports auto-commit. 
+	template <class Compare>
+	void sort(Compare comp)
+	{
+		try {
+			that->begin_txn();
+			std::sort(that->begin(), that->end(), comp);
+			that->commit_txn();
+		} catch (...) {
+			that->abort_txn();
+			throw;
+		}
+	}
+
+
+
+};
+
+
+template <typename T, typename T2>
+class _exported DbstlListSpecialOps<T*, T2>
+{
+	typedef db_vector<T*, T2> partner;
+	typedef typename partner::iterator iterator;
+	typedef typename partner::const_iterator const_iterator;
+	partner *that;
+	DbstlElemTraits<T> *inst;
+	typename DbstlElemTraits<T>::ElemSizeFunct sizef;
+	typename DbstlElemTraits<T>::SequenceLenFunct seqlenf;
+	typename DbstlElemTraits<T>::SequenceCopyFunct seqcopyf;
+	typename DbstlElemTraits<T>::SequenceCompareFunct seqcmpf;
+
+	void seq_assign(T *&dest, const T*src)
+	{
+		size_t sz = 0;
+		size_t seql = seqlenf(src);
+
+		
+		if (sizef == NULL)
+			sz = sizeof(T) * (seql + 1);
+		else {
+			
+			for (size_t i = 0; i < seql; i++)
+				sz += sizef(src[i]);
+			// Add space for terminating object, like '\0' 
+			// for char *string.
+			T tmp;
+			sz += sizef(tmp);
+		}
+		dest = (T *)DbstlReAlloc(dest, sz);
+		memset(dest, 0, sz);
+		seqcopyf(dest, src, seql);
+	}
+
+	template <typename T4>
+	class CompareInt
+	{
+		typename DbstlElemTraits<T4>::SequenceCompareFunct cmpf;
+	public:
+		CompareInt(typename DbstlElemTraits<T4>::
+		    SequenceCompareFunct cmpf1)
+		{
+			cmpf = cmpf1;
+		}
+
+		bool operator()(const std::basic_string<T4, 
+		    DbstlElemTraits<T4> >
+		    &a, const std::basic_string<T, DbstlElemTraits<T4> > &b)
+		{
+			return cmpf(a.c_str(), b.c_str());
+		}
+		
+	};
+
+	template <typename T4, typename Compare>
+	class CompareInt2
+	{
+	public:
+		Compare comp_;
+
+		CompareInt2(Compare comp)
+		{
+			comp_ = comp;
+		}
+
+		bool operator()(const std::basic_string<T4, 
+		    DbstlElemTraits<T4> >
+		    &s1, const std::basic_string<T4, DbstlElemTraits<T4> >& s2)
+		{
+			return comp_(s1.c_str(), s2.c_str());
+		}
+
+	};
+public:
+	DbstlListSpecialOps(partner *that1)
+	{
+		that = that1;
+
+		// Though he following settings are called in ResourceManager 
+		// singleton initialization, we still have to call them here 
+		// because the global variable in the dll is not the same one
+		// as the one in this application.
+		DbstlElemTraits<char> * cstarinst = 
+		    DbstlElemTraits<char>::instance();
+		cstarinst->set_sequence_len_function(dbstl_strlen);
+		cstarinst->set_sequence_copy_function(dbstl_strcpy);
+		cstarinst->set_sequence_compare_function(dbstl_strcmp);
+		cstarinst->set_sequence_n_compare_function(dbstl_strncmp);
+
+		DbstlElemTraits<wchar_t> *wcstarinst = 
+		    DbstlElemTraits<wchar_t>::instance();
+		wcstarinst->set_sequence_copy_function(dbstl_wcscpy);
+		wcstarinst->set_sequence_len_function(dbstl_wcslen);
+		wcstarinst->set_sequence_compare_function(dbstl_wcscmp);
+		wcstarinst->set_sequence_n_compare_function(dbstl_wcsncmp);
+
+		inst = DbstlElemTraits<T>::instance();
+		sizef = inst->get_size_function();
+		seqlenf = inst->get_sequence_len_function();
+		seqcopyf = inst->get_sequence_copy_function();
+		seqcmpf = inst->get_sequence_compare_function();
+	}
+
+	template <class BinaryPredicate>
+	void unique(BinaryPredicate binary_pred)
+	{
+		T *t2 = NULL;
+
+		try {
+			that->begin_txn();
+			iterator i = that->begin();
+			
+			seq_assign(t2, *i);
+			++i;
+			for (; i != that->end(); ++i) {
+				if (binary_pred(*i, t2))
+					that->erase(i);
+				else
+					seq_assign(t2, *i);
+			}
+			that->commit_txn();
+			free(t2);
+		} catch (...) {
+			that->abort_txn();
+			free(t2);
+			throw;
+		}
+	}
+
+	void unique()
+	{
+		T *t2 = NULL;
+
+		try {
+			that->begin_txn();
+			iterator i = that->begin();
+			seq_assign(t2, *i);
+			++i;
+			for (; i != that->end(); ++i) {
+				if (seqcmpf(*i, t2) == 0)
+					that->erase(i);
+				else
+					seq_assign(t2, *i);
+			}
+			that->commit_txn();
+			free(t2);
+		} catch (...) {
+			that->abort_txn();
+			free(t2);
+			throw;
+		}
+	}
+
+	/// This function supports auto-commit. 
+	void merge(partner& x)
+	{
+		that->verify_db_handles(x);
+		iterator itr, itrx;
+
+		try {
+			that->begin_txn();
+			for (itr = that->begin(), itrx = x.begin();
+			    itr != that->end() && itrx != x.end();) {
+				if (seqcmpf(*itr, *itrx) > 0) {
+					that->insert(itr, *itrx);
+					++itrx;
+				} else
+					++itr;
+			}
+			if (itr == that->end() && itrx != x.end())
+				that->insert(itr, itrx, x.end());
+			x.clear();
+			that->commit_txn();
+		} catch (...) {
+			that->abort_txn();
+			throw;
+		}
+	}
+
+	void sort()
+	{
+		try {
+			typedef std::basic_string<T, DbstlElemTraits<T> > 
+			    string_t;
+			CompareInt<T> comp(DbstlElemTraits<T>::instance()->
+			    get_sequence_compare_function());
+			std::list<string_t> tmplist(that->size());
+
+			that->begin_txn();
+			const_iterator itr;
+			const partner&cthat = *that;
+			typename std::list<string_t>::iterator itr1;
+
+			for (itr = cthat.begin(BulkRetrievalOption::
+			    bulk_retrieval()), itr1 = tmplist.begin();
+			    itr1 != tmplist.end(); ++itr, ++itr1)
+				*itr1 = string_t(*itr);
+
+			tmplist.sort();
+			that->clear(false);
+			for (typename std::list<string_t>::iterator 
+			    it = tmplist.begin(); 
+			    it != tmplist.end(); ++it)
+				that->push_back((T*)(it->c_str()));
+
+			that->commit_txn();
+		} catch (...) {
+			that->abort_txn();
+			throw;
+		}
+	}
+
+	/// This function supports auto-commit. 
+	template <class Compare>
+	void sort(Compare comp)
+	{
+		try {
+			typedef std::basic_string<T, DbstlElemTraits<T> > 
+			    string_t;
+			CompareInt2<T, Compare> comp2(comp);
+
+			std::list<string_t> tmplist(that->size());
+			that->begin_txn();
+			const_iterator itr;
+			const partner&cthat = *that;
+			typename std::list<string_t>::iterator itr1;
+
+			for (itr = cthat.begin(BulkRetrievalOption::
+			    bulk_retrieval()), itr1 = tmplist.begin();
+			    itr1 != tmplist.end(); ++itr, ++itr1)
+				*itr1 = string_t(*itr);
+
+			tmplist.sort(comp2);
+			that->clear(false);
+			for (typename std::list<string_t>::iterator it = 
+			    tmplist.begin(); 
+			    it != tmplist.end(); ++it)
+				that->push_back((T*)(it->c_str()));
+			
+			that->commit_txn();
+		} catch (...) {
+			that->abort_txn();
+			throw;
+		}
+	}
+
+
+};
+//@} //dbstl_containers
+END_NS
+#endif //_DB_STL_DB_VECTOR_H
+