<?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <title>Db::truncate()</title> <link rel="stylesheet" href="apiReference.css" type="text/css" /> <meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /> <link rel="start" href="index.html" title="Berkeley DB C++ API Reference" /> <link rel="up" href="db.html" title="Chapter 2. The Db Handle" /> <link rel="prev" href="dbsync.html" title="Db::sync()" /> <link rel="next" href="dbupgrade.html" title="Db::upgrade()" /> </head> <body> <div xmlns="" class="navheader"> <div class="libver"> <p>Library Version 11.2.5.3</p> </div> <table width="100%" summary="Navigation header"> <tr> <th colspan="3" align="center">Db::truncate()</th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="dbsync.html">Prev</a> </td> <th width="60%" align="center">Chapter 2. The Db Handle </th> <td width="20%" align="right"> <a accesskey="n" href="dbupgrade.html">Next</a></td> </tr> </table> <hr /> </div> <div class="sect1" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h2 class="title" style="clear: both"><a id="dbtruncate"></a>Db::truncate()</h2> </div> </div> </div> <pre class="programlisting">#include <db_cxx.h> int Db::truncate(DbTxn *txnid, u_int32_t *countp, u_int32_t flags);</pre> <p> The <code class="methodname">Db::truncate()</code> method empties the database, discarding all records it contains. The number of records discarded from the database is returned in <span class="bold"><strong>countp</strong></span>. </p> <p> When called on a database configured with secondary indices using the <a class="xref" href="dbassociate.html" title="Db::associate()">Db::associate()</a> method, the <code class="methodname">Db::truncate()</code> method truncates the primary database and all secondary indices. A count of the records discarded from the primary database is returned. </p> <p> It is an error to call the <code class="methodname">Db::truncate()</code> method on a database with open cursors. </p> <p> The <code class="methodname">Db::truncate()</code> <span> <span> method either returns a non-zero error value or throws an exception that encapsulates a non-zero error value on failure, and returns 0 on success. </span> </span> </p> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="idp646984"></a>Parameters</h3> </div> </div> </div> <div class="sect3" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h4 class="title"><a id="idp589704"></a>txnid</h4> </div> </div> </div> <p> If the operation is part of an application-specified transaction, the <span class="bold"><strong>txnid</strong></span> parameter is a transaction handle returned from <a class="xref" href="txnbegin.html" title="DbEnv::txn_begin()">DbEnv::txn_begin()</a>; if the operation is part of a Berkeley DB Concurrent Data Store group, the <span class="bold"><strong>txnid</strong></span> parameter is a handle returned from <a class="xref" href="envcdsgroup_begin.html" title="DbEnv::cdsgroup_begin()">DbEnv::cdsgroup_begin()</a>; otherwise NULL. If no transaction handle is specified, but the operation occurs in a transactional database, the operation will be implicitly transaction protected. </p> </div> <div class="sect3" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h4 class="title"><a id="idp634744"></a>countp</h4> </div> </div> </div> <p> The <span class="bold"><strong>countp</strong></span> parameter references memory into which the number of records discarded from the database is copied. </p> </div> <div class="sect3" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h4 class="title"><a id="idp631576"></a>flags</h4> </div> </div> </div> <p> The <span class="bold"><strong>flags</strong></span> parameter is currently unused, and must be set to 0. </p> </div> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="idp640096"></a>Errors</h3> </div> </div> </div> <p> The <code class="methodname">Db::truncate()</code> <span> <span> method may fail and throw a <a class="link" href="dbexception.html" title="Chapter 6. The DbException Class">DbException</a> exception, encapsulating one of the following non-zero errors, or return one of the following non-zero errors: </span> </span> </p> <div class="sect3" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h4 class="title"><a id="idp655480"></a><span>DbDeadlockException or </span>DB_LOCK_DEADLOCK</h4> </div> </div> </div> <p> A transactional database environment operation was selected to resolve a deadlock. </p> <p> <a class="xref" href="dbdeadlock.html" title="DbDeadlockException">DbDeadlockException</a> is thrown if your Berkeley DB API is configured to throw exceptions. Otherwise, <code class="literal">DB_LOCK_DEADLOCK</code> is returned. </p> </div> <div class="sect3" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h4 class="title"><a id="idp627368"></a><span>DbLockNotGrantedException or </span>DB_LOCK_NOTGRANTED</h4> </div> </div> </div> <p> A Berkeley DB Concurrent Data Store database environment configured for lock timeouts was unable to grant a lock in the allowed time. </p> <p> You attempted to open a database handle that is configured for no waiting exclusive locking, but the exclusive lock could not be immediately obtained. See <a class="xref" href="dbset_lk_exclusive.html" title="Db::set_lk_exclusive()">Db::set_lk_exclusive()</a> for more information. </p> <p> <a class="xref" href="dblocknotgranted.html" title="DbLockNotGrantedException">DbLockNotGrantedException</a> is thrown if your Berkeley DB API is configured to throw exceptions. Otherwise, <code class="literal">DB_LOCK_NOTGRANTED</code> is returned. </p> </div> <div class="sect3" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h4 class="title"><a id="idp647200"></a>EINVAL</h4> </div> </div> </div> <p> If there are open cursors in the database; or if an invalid flag value or parameter was specified. </p> </div> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="idp650816"></a>Class</h3> </div> </div> </div> <p> <a class="link" href="db.html" title="Chapter 2. The Db Handle">Db</a> </p> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="idp648016"></a>See Also</h3> </div> </div> </div> <p> <a class="xref" href="db.html#dblist" title="Database and Related Methods">Database and Related Methods</a> </p> </div> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="dbsync.html">Prev</a> </td> <td width="20%" align="center"> <a accesskey="u" href="db.html">Up</a> </td> <td width="40%" align="right"> <a accesskey="n" href="dbupgrade.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">Db::sync() </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> Db::upgrade()</td> </tr> </table> </div> </body> </html>