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183 lines
6.6 KiB
HTML
183 lines
6.6 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::set_priority()</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_partition_dirs.html" title="Db::set_partition_dirs()" />
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<link rel="next" href="dbset_q_extentsize.html" title="Db::set_q_extentsize()" />
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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::set_priority()</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_partition_dirs.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_q_extentsize.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_priority"></a>Db::set_priority()</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::set_priority(DB_CACHE_PRIORITY priority); </pre>
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<p>
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Set the cache priority for pages referenced by the
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<a class="link" href="db.html" title="Chapter 2. The Db Handle">Db</a> handle.
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</p>
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<p>
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The priority of a page biases the replacement algorithm to be more or
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less likely to discard a page when space is needed in the buffer pool.
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The bias is temporary, and pages will eventually be discarded if they
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are not referenced again. The <code class="methodname">Db::set_priority()</code> method is only
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advisory, and does not guarantee pages will be treated in a specific
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way.
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</p>
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<p>
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The <code class="methodname">Db::set_priority()</code> method may be called at any time during the
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life of the application.
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</p>
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<p>
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The <code class="methodname">Db::set_priority()</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="id3599112"></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="id3599101"></a>priority</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>priority</strong></span> parameter must be set to
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one of the following values:
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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><a id="set_priority_DB_PRIORITY_VERY_LOW"></a>
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<code class="literal">DB_PRIORITY_VERY_LOW</code>
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</p>
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<p>
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The lowest priority: pages are the most likely to be discarded.
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</p>
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</li>
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<li>
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<p><a id="set_priority_DB_PRIORITY_LOW"></a>
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<code class="literal">DB_PRIORITY_LOW</code>
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</p>
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<p>
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The next lowest priority.
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</p>
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</li>
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<li>
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<p><a id="set_priority_DB_PRIORITY_DEFAULT"></a>
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<code class="literal">DB_PRIORITY_DEFAULT</code>
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</p>
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<p>
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The default priority.
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</p>
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</li>
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<li>
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<p><a id="set_priority_DB_PRIORITY_HIGH"></a>
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<code class="literal">DB_PRIORITY_HIGH</code>
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</p>
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<p>
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The next highest priority.
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</p>
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</li>
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<li>
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<p><a id="set_priority_DB_PRIORITY_VERY_HIGH"></a>
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<code class="literal">DB_PRIORITY_VERY_HIGH</code>
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</p>
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<p>
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The highest priority: pages are the least likely to be discarded.
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</p>
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</li>
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</ul>
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</div>
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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="id3599273"></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="id3598790"></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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|||
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<td width="40%" align="left"><a accesskey="p" href="dbset_partition_dirs.html">Prev</a> </td>
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|||
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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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|||
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</td>
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|||
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<td width="40%" align="right"> <a accesskey="n" href="dbset_q_extentsize.html">Next</a></td>
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|||
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</tr>
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|||
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<tr>
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<td width="40%" align="left" valign="top">Db::set_partition_dirs() </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_q_extentsize()</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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