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224 lines
9.1 KiB
HTML
<?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->set_append_recno()</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="dbset_alloc.html" title="DB->set_alloc()" />
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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 11.2.5.3</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->set_append_recno()</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="dbset_alloc.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="dbset_bt_compare.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="dbset_append_recno"></a>DB->set_append_recno()</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.h>
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int
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DB->set_append_recno(DB *,
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int (*db_append_recno_fcn)(DB *dbp, DBT *data, db_recno_t recno)); </pre>
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<p>
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When using the <a class="link" href="dbput.html#dbput_DB_APPEND">DB_APPEND</a>
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option of the <a class="xref" href="dbput.html" title="DB->put()">DB->put()</a> method, it may be
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useful to modify the stored data based on the generated key. If a
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callback function is specified using the
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<code class="methodname">DB->set_append_recno()</code>
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method, it will be called after the record number has been selected,
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but before the data has been stored.
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</p>
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<p>
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The <code class="methodname">DB->set_append_recno()</code> method configures operations performed
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using the specified <a class="link" href="db.html" title="Chapter 2. The DB Handle">DB</a>
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handle, not all operations performed on the underlying database.
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</p>
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<p>
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The <code class="methodname">DB->set_append_recno()</code> method may not be called after the
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<a class="xref" href="dbopen.html" title="DB->open()">DB->open()</a> method is called.
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</p>
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<p>
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The <code class="methodname">DB->set_append_recno()</code> <span>
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<span>
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method returns a non-zero error value on failure and 0 on success.
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</span>
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</span>
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</p>
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<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
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<h3 class="title">Note</h3>
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<p>
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Berkeley DB is not re-entrant. Callback functions should not attempt to make
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library calls (for example, to release locks or close open handles). Re-entering
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Berkeley DB is not guaranteed to work correctly, and the results are undefined.
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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="idp58047176"></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="idp58055712"></a>db_append_recno_fcn</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>db_append_recno_fcn</strong></span> parameter is
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a function to call after the record number has been selected but
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before the data has been stored into the database. The function takes
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three parameters:
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</p>
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<div class="itemizedlist">
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<ul type="disc">
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<li>
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<p>
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<code class="literal">dbp</code>
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</p>
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<p>
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The <span class="bold"><strong>dbp</strong></span> parameter is the enclosing
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database handle.
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</p>
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</li>
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<li>
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<p>
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<code class="literal">data</code>
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</p>
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<p>
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The <span class="bold"><strong>data</strong></span> parameter is the data
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<a class="link" href="dbt.html" title="Chapter 4. The DBT Handle">DBT</a> to be stored.
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</p>
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</li>
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<li>
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<p>
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<code class="literal">recno</code>
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</p>
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<p>
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The <span class="bold"><strong>recno</strong></span> parameter is the generated
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record number.
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</p>
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</li>
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</ul>
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</div>
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<p>
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The called function may modify the data
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<a class="link" href="dbt.html" title="Chapter 4. The DBT Handle">DBT</a>. If the function needs to allocate
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memory for the <span class="bold"><strong>data</strong></span> field, the
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<span class="bold"><strong>flags</strong></span> field of
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the returned <a class="link" href="dbt.html" title="Chapter 4. The DBT Handle">DBT</a>
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should be set to <code class="literal">DB_DBT_APPMALLOC</code>, which indicates that
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Berkeley DB should free the memory when it is done with it.
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</p>
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<p>
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The callback function must return 0 on success and
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<span class="bold"><strong>errno</strong></span> or a value outside of
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the Berkeley DB error name space on failure.
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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="idp58069376"></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->set_append_recno()</code> <span>
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<span>
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method may fail and return one 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="idp58064768"></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 method was called after <a class="xref" href="dbopen.html" title="DB->open()">DB->open()</a>
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was called; 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>
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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="idp58065848"></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="idp58060968"></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="dbset_alloc.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="dbset_bt_compare.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->set_alloc() </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->set_bt_compare()</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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