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<!--Id: db_truncate.so,v 1.6 2001/04/18 13:44:46 bostic Exp -->
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<title>Berkeley DB: DB->truncate</title>
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<h1>DB->truncate</h1>
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<h3><pre>
#include <db.h>
<p>
int
DB->truncate(DB *db, const char *file,
const char *database, u_int32_t *countp, u_int32_t flags);
</pre></h3>
<h1>Description</h1>
<p>The DB->truncate interface empties the database specified by
the <b>file</b> and <b>database</b> arguments, discarding all records
it contains. If no <b>database</b> is specified, the underlying file
represented by <b>file</b> is emptied.
The number of records discarded from the database is returned in
<b>countp</b>.
<p>Truncate must have exclusive use of the database. While truncate is
transaction-protected, it cannot be part of a application-created
transaction.
<p>The <b>flags</b> parameter is currently unused, and must be set to 0.
<p>After DB->truncate has been called, regardless of its return,
the DB handle may not be accessed again.
<p>The DB->truncate function returns a non-zero error value on failure and 0 on success.
<h1>Environment Variables</h1>
<p><dl compact>
<p><dt>DB_HOME<dd>If the <b>dbenv</b> argument to <a href="../api_c/db_create.html">db_create</a> was initialized using
<a href="../api_c/env_open.html">DBENV->open</a>, the environment variable <b>DB_HOME</b> may be used
as the path of the database environment home. Specifically, DB->truncate
is affected by the configuration value DB_DATA_DIR.
</dl>
<h1>Errors</h1>
<p>The DB->truncate function may fail and return a non-zero error for the following conditions:
<p><dl compact>
<p><dt>EINVAL<dd>A database in the file is currently open.
</dl>
<p>The DB->truncate function may fail and return a non-zero error for errors specified for other Berkeley DB and C library or system functions.
If a catastrophic error has occurred, the DB->truncate function may fail and return
<a href="../ref/program/errorret.html#DB_RUNRECOVERY">DB_RUNRECOVERY</a>, in which case all subsequent Berkeley DB calls will fail
in the same way.
<h1>See Also</h1>
<a href="../api_c/db_create.html">db_create</a>,
<a href="../api_c/db_associate.html">DB->associate</a>,
<a href="../api_c/db_close.html">DB->close</a>,
<a href="../api_c/db_cursor.html">DB->cursor</a>,
<a href="../api_c/db_del.html">DB->del</a>,
<a href="../api_c/db_err.html">DB->err</a>, <a href="../api_c/db_err.html">DB->errx</a>
<a href="../api_c/db_fd.html">DB->fd</a>,
<a href="../api_c/db_get.html">DB->get</a>,
<a href="../api_c/db_get.html">DB->pget</a>,
<a href="../api_c/db_get_byteswapped.html">DB->get_byteswapped</a>,
<a href="../api_c/db_get_type.html">DB->get_type</a>,
<a href="../api_c/db_join.html">DB->join</a>,
<a href="../api_c/db_key_range.html">DB->key_range</a>,
<a href="../api_c/db_open.html">DB->open</a>,
<a href="../api_c/db_put.html">DB->put</a>,
<a href="../api_c/db_remove.html">DB->remove</a>,
<a href="../api_c/db_rename.html">DB->rename</a>,
<a href="../api_c/db_set_alloc.html">DB->set_alloc</a>,
<a href="../api_c/db_set_append_recno.html">DB->set_append_recno</a>,
<a href="../api_c/db_set_bt_compare.html">DB->set_bt_compare</a>,
<a href="../api_c/db_set_bt_minkey.html">DB->set_bt_minkey</a>,
<a href="../api_c/db_set_bt_prefix.html">DB->set_bt_prefix</a>,
<a href="../api_c/db_set_cachesize.html">DB->set_cachesize</a>,
<a href="../api_c/db_set_dup_compare.html">DB->set_dup_compare</a>,
<a href="../api_c/db_set_errcall.html">DB->set_errcall</a>,
<a href="../api_c/db_set_errfile.html">DB->set_errfile</a>,
<a href="../api_c/db_set_errpfx.html">DB->set_errpfx</a>,
<a href="../api_c/db_set_feedback.html">DB->set_feedback</a>,
<a href="../api_c/db_set_flags.html">DB->set_flags</a>,
<a href="../api_c/db_set_h_ffactor.html">DB->set_h_ffactor</a>,
<a href="../api_c/db_set_h_hash.html">DB->set_h_hash</a>,
<a href="../api_c/db_set_h_nelem.html">DB->set_h_nelem</a>,
<a href="../api_c/db_set_lorder.html">DB->set_lorder</a>,
<a href="../api_c/db_set_pagesize.html">DB->set_pagesize</a>,
<a href="../api_c/db_set_paniccall.html">DB->set_paniccall</a>,
<a href="../api_c/db_set_q_extentsize.html">DB->set_q_extentsize</a>,
<a href="../api_c/db_set_re_delim.html">DB->set_re_delim</a>,
<a href="../api_c/db_set_re_len.html">DB->set_re_len</a>,
<a href="../api_c/db_set_re_pad.html">DB->set_re_pad</a>,
<a href="../api_c/db_set_re_source.html">DB->set_re_source</a>,
<a href="../api_c/db_stat.html">DB->stat</a>,
<a href="../api_c/db_sync.html">DB->sync</a>,
<a href="../api_c/db_truncate.html">DB->truncate</a>,
<a href="../api_c/db_upgrade.html">DB->upgrade</a>,
and
<a href="../api_c/db_verify.html">DB->verify</a>.
</tt>
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