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HTML
202 lines
8.1 KiB
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<?xml version="1.0" encoding="UTF-8" standalone="no"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
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<title>DbTxn::prepare()</title>
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<link rel="stylesheet" href="apiReference.css" type="text/css" />
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<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
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<link rel="start" href="index.html" title="Berkeley DB C++ API Reference" />
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<link rel="up" href="txn.html" title="Chapter 13. The DbTxn Handle" />
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<link rel="prev" href="txnid.html" title="DbTxn::id()" />
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<link rel="next" href="txnset_name.html" title="DbTxn::set_name()" />
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</head>
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<body>
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<div xmlns="" class="navheader">
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<div class="libver">
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<p>Library Version 11.2.5.2</p>
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</div>
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<table width="100%" summary="Navigation header">
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<tr>
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<th colspan="3" align="center">DbTxn::prepare()</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="txnid.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 13.
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The DbTxn Handle
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</th>
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<td width="20%" align="right"> <a accesskey="n" href="txnset_name.html">Next</a></td>
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</tr>
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</table>
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<hr />
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</div>
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<div class="sect1" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h2 class="title" style="clear: both"><a id="txnprepare"></a>DbTxn::prepare()</h2>
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</div>
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</div>
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</div>
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<pre class="programlisting">#include <db_cxx.h>
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int
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DbTxn::prepare(u_int8_t gid[DB_GID_SIZE]);</pre>
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<p>
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The <code class="methodname">DbTxn::prepare()</code> method initiates the beginning of a two-phase
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commit.
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</p>
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<p>
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In a distributed transaction environment, Berkeley DB can be used as a
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local transaction manager. In this case, the distributed transaction
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manager must send <span class="emphasis"><em>prepare</em></span> messages to each local
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manager. The local manager must then issue a <code class="methodname">DbTxn::prepare()</code> and
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await its successful return before responding to the distributed
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transaction manager. Only after the distributed transaction manager
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receives successful responses from all of its
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<span class="emphasis"><em>prepare</em></span> messages should it issue any
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<span class="emphasis"><em>commit</em></span> messages.
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</p>
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<p>
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In the case of nested transactions, preparing the parent causes all
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unresolved children of the parent transaction to be committed. Child
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transactions should never be explicitly prepared. Their fate will be
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resolved along with their parent's during global recovery.
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</p>
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<p>
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All open cursors in the transaction are closed and the
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first cursor close error will be returned.
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</p>
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<p>
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The <code class="methodname">DbTxn::prepare()</code> <span>
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<span>
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method either returns a non-zero error value or throws an
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exception that encapsulates a non-zero error value on
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failure, and returns 0 on success.
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</span>
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</span>
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The errors that this method returns include the error values of <code class="methodname">Dbc::close()</code> and the following:
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</p>
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<div class="sect3" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h4 class="title"><a id="id3674496"></a><span>DbDeadlockException or </span>DB_LOCK_DEADLOCK</h4>
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</div>
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</div>
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</div>
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<p>
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A transactional database environment operation was selected to resolve
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a deadlock.
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</p>
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<p>
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<a class="xref" href="dbdeadlock.html" title="DbDeadlockException">DbDeadlockException</a> is thrown if
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your Berkeley DB API is configured to throw exceptions.
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Otherwise, <code class="literal">DB_LOCK_DEADLOCK</code> is returned.
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</p>
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</div>
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<div class="sect3" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h4 class="title"><a id="id3674364"></a><span>DbLockNotGrantedException or </span>DB_LOCK_NOTGRANTED</h4>
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</div>
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</div>
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</div>
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<p>
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A Berkeley DB Concurrent Data Store database environment configured
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for lock timeouts was unable to grant a lock in the allowed time.
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</p>
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<p>
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<a class="xref" href="dblocknotgranted.html" title="DbLockNotGrantedException">DbLockNotGrantedException</a> is thrown if
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your Berkeley DB API is configured to throw exceptions.
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Otherwise, <code class="literal">DB_LOCK_NOTGRANTED</code> is returned.
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</p>
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</div>
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<div class="sect3" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h4 class="title"><a id="id3674328"></a>EINVAL</h4>
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</div>
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</div>
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</div>
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<p>
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If the cursor is already closed; or if an invalid flag value or parameter was specified.
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</p>
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</div>
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<div class="sect2" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h3 class="title"><a id="id3674812"></a>Parameters</h3>
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</div>
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</div>
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</div>
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<div class="sect3" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h4 class="title"><a id="id3674815"></a>gid</h4>
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</div>
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</div>
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</div>
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<p>
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The <span class="bold"><strong>gid</strong></span> parameter specifies the
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global transaction ID by which this transaction will be known. This
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global transaction ID will be returned in calls
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to <a class="xref" href="txnrecover.html" title="DbEnv::txn_recover()">DbEnv::txn_recover()</a>
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telling the application which global transactions must be resolved.
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</p>
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</div>
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</div>
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<div class="sect2" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h3 class="title"><a id="id3674694"></a>Class</h3>
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</div>
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</div>
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</div>
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<p>
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<a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a>, <a class="link" href="txn.html" title="Chapter 13. The DbTxn Handle">DbTxn</a>
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</p>
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</div>
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<div class="sect2" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h3 class="title"><a id="id3674714"></a>See Also</h3>
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</div>
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</div>
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</div>
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<p>
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<a class="xref" href="txn.html#txnlist" title="Transaction Subsystem and Related Methods">Transaction Subsystem and Related Methods</a>
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</p>
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</div>
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</div>
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<div class="navfooter">
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<hr />
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<table width="100%" summary="Navigation footer">
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<tr>
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<td width="40%" align="left"><a accesskey="p" href="txnid.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="txn.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="txnset_name.html">Next</a></td>
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</tr>
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<tr>
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<td width="40%" align="left" valign="top">DbTxn::id() </td>
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<td width="20%" align="center">
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<a accesskey="h" href="index.html">Home</a>
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</td>
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<td width="40%" align="right" valign="top"> DbTxn::set_name()</td>
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</tr>
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</table>
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</div>
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</body>
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</html>
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