1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
|
<!--$Id: get.so,v 10.18 2003/10/18 19:15:52 bostic Exp $-->
<!--Copyright 1997-2006 by Oracle Corporation-->
<!--All rights reserved.-->
<!--See the file LICENSE for redistribution information.-->
<html>
<head>
<title>Berkeley DB Reference Guide: Retrieving records</title>
<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit.">
<meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++">
</head>
<body bgcolor=white>
<a name="2"><!--meow--></a>
<table width="100%"><tr valign=top>
<td><h3><dl><dt>Berkeley DB Reference Guide:<dd>Access Methods</dl></h3></td>
<td align=right><a href="../am/opensub.html"><img src="../../images/prev.gif" alt="Prev"></a><a href="../toc.html"><img src="../../images/ref.gif" alt="Ref"></a><a href="../am/put.html"><img src="../../images/next.gif" alt="Next"></a>
</td></tr></table>
<p>
<h3 align=center>Retrieving records</h3>
<p>The <a href="../../api_c/db_get.html">DB->get</a> method retrieves records from the database. In general,
<a href="../../api_c/db_get.html">DB->get</a> takes a key and returns the associated data from the
database.</p>
<p>There are a few flags that you can set to customize retrieval:</p>
<dl compact>
<dt><a href="../../api_c/db_get.html#DB_GET_BOTH">DB_GET_BOTH</a><dd>Search for a matching key and data item, that is, only return success
if both the key and the data items match those stored in the database.
<dt><a href="../../api_c/dbc_get.html#DB_RMW">DB_RMW</a><dd>Read-modify-write: acquire write locks instead of read locks during
retrieval. This can enhance performance in threaded applications by
reducing the chance of deadlock.
<dt><a href="../../api_c/db_get.html#DB_SET_RECNO">DB_SET_RECNO</a><dd>If the underlying database is a Btree, and was configured so that it
is possible to search it by logical record number, retrieve a specific
record.
</dl>
<p>If the database has been configured to support duplicate records,
<a href="../../api_c/db_get.html">DB->get</a> will always return the first data item in the duplicate
set.</p>
<table width="100%"><tr><td><br></td><td align=right><a href="../am/opensub.html"><img src="../../images/prev.gif" alt="Prev"></a><a href="../toc.html"><img src="../../images/ref.gif" alt="Ref"></a><a href="../am/put.html"><img src="../../images/next.gif" alt="Next"></a>
</td></tr></table>
<p><font size=1>Copyright (c) 1996-2006 Oracle Corporation - All rights reserved.</font>
</body>
</html>
|
