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216 lines
8.4 KiB
HTML
216 lines
8.4 KiB
HTML
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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>Db::sync()</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="db.html" title="Chapter 2. The Db Handle" />
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<link rel="prev" href="dbstat_print.html" title="Db::stat_print()" />
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<link rel="next" href="dbtruncate.html" title="Db::truncate()" />
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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">Db::sync()</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="dbstat_print.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 2.
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The Db Handle
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</th>
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<td width="20%" align="right"> <a accesskey="n" href="dbtruncate.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="dbsync"></a>Db::sync()</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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Db::sync(u_int32_t flags);</pre>
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<p>
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The <code class="methodname">Db::sync()</code> method flushes any cached information to disk.
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This method operates on the database file level, so if the file
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contains multiple database handles then this method will flush to
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disk any information that is cached for any of those handles.
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</p>
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<p>
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If the database is in memory only, the <code class="methodname">Db::sync()</code> method has no
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effect and will always succeed.
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</p>
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<p>
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<span class="bold"><strong>It is important to understand that flushing
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cached information to disk only minimizes the window of opportunity
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for corrupted data.</strong></span> Although unlikely, it is possible for
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database corruption to happen if a system or application crash occurs
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while writing data to the database. To ensure that database
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corruption never occurs, applications must either: use transactions
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and logging with automatic recovery; use logging and
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application-specific recovery; or edit a copy of the database, and
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once all applications using the database have successfully called
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<a class="xref" href="dbclose.html" title="Db::close()">Db::close()</a>, atomically
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replace the original database with the updated copy.
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</p>
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<p>
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The <code class="methodname">Db::sync()</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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</p>
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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="id3602063"></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="id3602055"></a>flags</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>flags</strong></span> parameter is currently
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unused, and must be set to 0.
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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="id3600263"></a>Errors</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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The <code class="methodname">Db::sync()</code> <span>
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<span>
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method may fail and throw a <a class="link" href="dbexception.html" title="Chapter 6. The DbException Class">DbException</a>
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exception, encapsulating one of the following non-zero errors, or return one
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of the following non-zero errors:
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</span>
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</span>
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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="id3602139"></a> <span>DbRepHandleDeadException or</span> DB_REP_HANDLE_DEAD</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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When a client synchronizes with the master, it is possible for committed
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transactions to be rolled back. This invalidates all the database and cursor
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handles opened in the replication environment. Once this occurs, an attempt to use
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such a handle will
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<span>
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throw a <a class="xref" href="dbrephandledead.html" title="DbRepHandleDeadException">DbRepHandleDeadException</a> (if
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your application is configured to throw exceptions), or
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</span>
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return <code class="literal">DB_REP_HANDLE_DEAD</code>.
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The application will need to discard the handle and open a new one in order to
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continue processing.
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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="id3601902"></a><span>DbDeadlockException or </span>DB_REP_LOCKOUT</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 operation was blocked by client/master synchronization.
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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_REP_LOCKOUT</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="id3600526"></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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An invalid flag value or parameter was specified.
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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="id3601351"></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="db.html" title="Chapter 2. The Db Handle">Db</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="id3602209"></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="db.html#dblist" title="Database and Related Methods">Database 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="dbstat_print.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="db.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="dbtruncate.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">Db::stat_print() </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"> Db::truncate()</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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