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HTML
194 lines
7.3 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>DB_MPOOLFILE->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="memp.html" title="Chapter 8. The DB_MPOOLFILE Handle" />
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<link rel="prev" href="mempset_pgcookie.html" title="DB_MPOOLFILE->set_pgcookie()" />
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<link rel="next" href="mutex.html" title="Chapter 9. Mutex Methods" />
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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_MPOOLFILE->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="mempset_pgcookie.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 8.
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The DB_MPOOLFILE Handle
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</th>
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<td width="20%" align="right"> <a accesskey="n" href="mutex.html">Next</a></td>
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</tr>
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</table>
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<hr />
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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="mempset_priority"></a>DB_MPOOLFILE->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.h>
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int
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DB_MPOOLFILE->set_priority(DB_MPOOLFILE *mpf, 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="memp.html" title="Chapter 8. The DB_MPOOLFILE Handle">DB_MPOOLFILE</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 cache.
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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_MPOOLFILE->set_priority()</code> method is
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only advisory, and does not guarantee pages will be treated in a
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specific way.
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</p>
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<p>
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To set the priority for the pages belonging to a particular database,
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call the <code class="methodname">DB_MPOOLFILE->set_priority()</code> method using the
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<a class="link" href="memp.html" title="Chapter 8. The DB_MPOOLFILE Handle">DB_MPOOLFILE</a> handle
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returned by the <a class="xref" href="dbget_mpf.html" title="DB->get_mpf()">DB->get_mpf()</a> method.
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</p>
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<p>
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The <code class="methodname">DB_MPOOLFILE->set_priority()</code> method configures a file in the
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cache, not only operations performed using the specified
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<a class="link" href="memp.html" title="Chapter 8. The DB_MPOOLFILE Handle">DB_MPOOLFILE</a> handle.
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</p>
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<p>
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The <code class="methodname">DB_MPOOLFILE->set_priority()</code> method may be called at any time
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during the life of the application.
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</p>
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<p>
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The <code class="methodname">DB_MPOOLFILE->set_priority()</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="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="id3920930"></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="id3920919"></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>
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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>
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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>
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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>
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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>
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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="id3921183"></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 DB_ENV Handle">DB_ENV</a>, <a class="link" href="memp.html" title="Chapter 8. The DB_MPOOLFILE Handle">DB_MPOOLFILE</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="id3921013"></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="memp.html#memplist" title="Memory Pools and Related Methods">Memory Pools 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="mempset_pgcookie.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="memp.html">Up</a>
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</td>
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|||
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<td width="40%" align="right"> <a accesskey="n" href="mutex.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_MPOOLFILE->set_pgcookie() </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"> Chapter 9.
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Mutex Methods
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</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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