<?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <title>Db::set_priority()</title> <link rel="stylesheet" href="apiReference.css" type="text/css" /> <meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /> <link rel="start" href="index.html" title="Berkeley DB C++ API Reference" /> <link rel="up" href="db.html" title="Chapter 2. The Db Handle" /> <link rel="prev" href="dbset_partition_dirs.html" title="Db::set_partition_dirs()" /> <link rel="next" href="dbset_q_extentsize.html" title="Db::set_q_extentsize()" /> </head> <body> <div xmlns="" class="navheader"> <div class="libver"> <p>Library Version 11.2.5.3</p> </div> <table width="100%" summary="Navigation header"> <tr> <th colspan="3" align="center">Db::set_priority()</th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="dbset_partition_dirs.html">Prev</a> </td> <th width="60%" align="center">Chapter 2. The Db Handle </th> <td width="20%" align="right"> <a accesskey="n" href="dbset_q_extentsize.html">Next</a></td> </tr> </table> <hr /> </div> <div class="sect1" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h2 class="title" style="clear: both"><a id="dbset_priority"></a>Db::set_priority()</h2> </div> </div> </div> <pre class="programlisting">#include <db_cxx.h> int Db::set_priority(DB_CACHE_PRIORITY priority); </pre> <p> Set the cache priority for pages referenced by the <a class="link" href="db.html" title="Chapter 2. The Db Handle">Db</a> handle. </p> <p> The priority of a page biases the replacement algorithm to be more or less likely to discard a page when space is needed in the buffer pool. The bias is temporary, and pages will eventually be discarded if they are not referenced again. The <code class="methodname">Db::set_priority()</code> method is only advisory, and does not guarantee pages will be treated in a specific way. </p> <p> The <code class="methodname">Db::set_priority()</code> method may be called at any time during the life of the application. </p> <p> The <code class="methodname">Db::set_priority()</code> <span> <span> method either returns a non-zero error value or throws an exception that encapsulates a non-zero error value on failure, and returns 0 on success. </span> </span> </p> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="idp5783368"></a>Parameters</h3> </div> </div> </div> <div class="sect3" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h4 class="title"><a id="idp5782720"></a>priority</h4> </div> </div> </div> <p> The <span class="bold"><strong>priority</strong></span> parameter must be set to one of the following values: </p> <div class="itemizedlist"> <ul type="disc"> <li> <p><a id="set_priority_DB_PRIORITY_VERY_LOW"></a> <code class="literal">DB_PRIORITY_VERY_LOW</code> </p> <p> The lowest priority: pages are the most likely to be discarded. </p> </li> <li> <p><a id="set_priority_DB_PRIORITY_LOW"></a> <code class="literal">DB_PRIORITY_LOW</code> </p> <p> The next lowest priority. </p> </li> <li> <p><a id="set_priority_DB_PRIORITY_DEFAULT"></a> <code class="literal">DB_PRIORITY_DEFAULT</code> </p> <p> The default priority. </p> </li> <li> <p><a id="set_priority_DB_PRIORITY_HIGH"></a> <code class="literal">DB_PRIORITY_HIGH</code> </p> <p> The next highest priority. </p> </li> <li> <p><a id="set_priority_DB_PRIORITY_VERY_HIGH"></a> <code class="literal">DB_PRIORITY_VERY_HIGH</code> </p> <p> The highest priority: pages are the least likely to be discarded. </p> </li> </ul> </div> </div> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="idp5793016"></a>Class</h3> </div> </div> </div> <p> <a class="link" href="db.html" title="Chapter 2. The Db Handle">Db</a> </p> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="idp5767488"></a>See Also</h3> </div> </div> </div> <p> <a class="xref" href="db.html#dblist" title="Database and Related Methods">Database and Related Methods</a> </p> </div> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="dbset_partition_dirs.html">Prev</a> </td> <td width="20%" align="center"> <a accesskey="u" href="db.html">Up</a> </td> <td width="40%" align="right"> <a accesskey="n" href="dbset_q_extentsize.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">Db::set_partition_dirs() </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> Db::set_q_extentsize()</td> </tr> </table> </div> </body> </html>