<!--$Id: db_truncate.html,v 1.2 2004/03/30 01:21:57 jtownsen Exp $--> <!--Copyright 1997-2003 by Sleepycat Software, Inc.--> <!--All rights reserved.--> <!--See the file LICENSE for redistribution information.--> <html> <head> <title>Berkeley DB: Db::truncate</title> <meta name="description" content="Berkeley DB: An embedded database programmatic toolkit."> <meta name="keywords" content="embedded,database,programmatic,toolkit,b+tree,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>Db::truncate</h3> </td> <td align=right> <a href="../api_cxx/api_index.html"><img src="../images/api.gif" alt="API"></a> <a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a> </td></tr></table> <hr size=1 noshade> <tt> <h3><pre> #include <db_cxx.h> <p> int Db::truncate(DbTxn *txnid, u_int32_t *countp, u_int32_t flags); </pre></h3> <hr size=1 noshade> <h3>Description: Db::truncate</h3> <p>The Db::truncate method empties the database, discarding all records it contains. The number of records discarded from the database is returned in <b>countp</b>.</p> <p>It is an error to call the Db::truncate method on a database with open cursors.</p> <p>The Db::truncate 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. </p> <h3>Parameters</h3> <p><dl compact> <p><dt><b>countp</b><dd> The <b>countp</b> parameter references memory into which the number of records discarded from the database is copied. <p><dt><b>flags</b><dd> The <b>flags</b> parameter must be set to 0 or the following value: <p><dl compact> <p><dt><a name="DB_AUTO_COMMIT">DB_AUTO_COMMIT</a><dd>Enclose the Db::truncate call within a transaction. If the call succeeds, changes made by the operation will be recoverable. If the call fails, the operation will have made no changes. </dl> <p><dt><b>txnid</b><dd> If the operation is to be transaction-protected, (other than by specifying the DB_AUTO_COMMIT flag), the <b>txnid</b> parameter is a transaction handle returned from <a href="../api_cxx/txn_begin.html">DbEnv::txn_begin</a>; otherwise, NULL. </dl> <h3>Errors</h3> <p>The Db::truncate method may fail and throw <a href="../api_cxx/except_class.html">DbException</a>, encapsulating one of the following non-zero errors, or return one of the following non-zero errors:</p> <p><dl compact> <p><dt>EINVAL<dd>If there are open cursors in the database; or if an invalid flag value or parameter was specified. </dl> <p>If a transactional database environment operation was selected to resolve a deadlock, the Db::truncate method will fail and either return <a href="../ref/program/errorret.html#DB_LOCK_DEADLOCK">DB_LOCK_DEADLOCK</a> or throw a <a href="../api_cxx/deadlock_class.html">DbDeadlockException</a> exception.</p> <p>If a Berkeley DB Concurrent Data Store database environment configured for lock timeouts was unable to grant a lock in the allowed time, the Db::truncate method will fail and either return <a href="../ref/program/errorret.html#DB_LOCK_NOTGRANTED">DB_LOCK_NOTGRANTED</a> or throw a <a href="../api_cxx/lockng_class.html">DbLockNotGrantedException</a> exception.</p> <hr size=1 noshade> <h3>Class</h3> <a href="../api_cxx/db_class.html">Db</a> <h3>See Also</h3> <a href="../api_cxx/db_list.html">Databases and Related Methods</a> </tt> <table width="100%"><tr><td><br></td><td align=right> <a href="../api_cxx/api_index.html"><img src="../images/api.gif" alt="API"></a><a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a> </td></tr></table> <p><font size=1><a href="../sleepycat/legal.html">Copyright (c) 1996-2003</a> <a href="http://www.sleepycat.com">Sleepycat Software, Inc.</a> - All rights reserved.</font> </body> </html>