1<?xml version="1.0" encoding="UTF-8" standalone="no"?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 3<html xmlns="http://www.w3.org/1999/xhtml"> 4 <head> 5 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> 6 <title>DB->set_priority()</title> 7 <link rel="stylesheet" href="apiReference.css" type="text/css" /> 8 <meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /> 9 <link rel="start" href="index.html" title="Berkeley DB C API Reference" /> 10 <link rel="up" href="db.html" title="Chapter��2.�� The DB Handle" /> 11 <link rel="prev" href="dbset_partition_dirs.html" title="DB->set_partition_dirs()" /> 12 <link rel="next" href="dbset_q_extentsize.html" title="DB->set_q_extentsize()" /> 13 </head> 14 <body> 15 <div class="navheader"> 16 <table width="100%" summary="Navigation header"> 17 <tr> 18 <th colspan="3" align="center">DB->set_priority()</th> 19 </tr> 20 <tr> 21 <td width="20%" align="left"><a accesskey="p" href="dbset_partition_dirs.html">Prev</a>��</td> 22 <th width="60%" align="center">Chapter��2.�� 23 The DB Handle 24 </th> 25 <td width="20%" align="right">��<a accesskey="n" href="dbset_q_extentsize.html">Next</a></td> 26 </tr> 27 </table> 28 <hr /> 29 </div> 30 <div class="sect1" lang="en" xml:lang="en"> 31 <div class="titlepage"> 32 <div> 33 <div> 34 <h2 class="title" style="clear: both"><a id="dbset_priority"></a>DB->set_priority()</h2> 35 </div> 36 </div> 37 </div> 38 <pre class="programlisting">#include <db.h> 39 40int 41DB->set_priority(DB *db, DB_CACHE_PRIORITY priority); </pre> 42 <p> 43 Set the cache priority for pages referenced by the 44 <a class="link" href="db.html" title="Chapter��2.�� The DB Handle">DB</a> handle. 45 </p> 46 <p> 47 The priority of a page biases the replacement algorithm to be more or 48 less likely to discard a page when space is needed in the buffer pool. 49 The bias is temporary, and pages will eventually be discarded if they 50 are not referenced again. The <code class="methodname">DB->set_priority()</code> method is only 51 advisory, and does not guarantee pages will be treated in a specific 52 way. 53 </p> 54 <p> 55 The <code class="methodname">DB->set_priority()</code> method may be called at any time during the 56 life of the application. 57 </p> 58 <p> 59 The <code class="methodname">DB->set_priority()</code> <span> 60 <span> 61 method returns a non-zero error value on failure and 0 on success. 62 </span> 63 64 </span> 65 </p> 66 <div class="sect2" lang="en" xml:lang="en"> 67 <div class="titlepage"> 68 <div> 69 <div> 70 <h3 class="title"><a id="id1649442"></a>Parameters</h3> 71 </div> 72 </div> 73 </div> 74 <div class="sect3" lang="en" xml:lang="en"> 75 <div class="titlepage"> 76 <div> 77 <div> 78 <h4 class="title"><a id="id1649128"></a>priority</h4> 79 </div> 80 </div> 81 </div> 82 <p> 83 The <span class="bold"><strong>priority</strong></span> parameter must be set to 84 one of the following values: 85 </p> 86 <div class="itemizedlist"> 87 <ul type="disc"> 88 <li> 89 <p><a id="set_priority_DB_PRIORITY_VERY_LOW"></a> 90 <code class="literal">DB_PRIORITY_VERY_LOW</code> 91 </p> 92 <p> 93 The lowest priority: pages are the most likely to be discarded. 94 </p> 95 </li> 96 <li> 97 <p><a id="set_priority_DB_PRIORITY_LOW"></a> 98 <code class="literal">DB_PRIORITY_LOW</code> 99 </p> 100 <p> 101 The next lowest priority. 102 </p> 103 </li> 104 <li> 105 <p><a id="set_priority_DB_PRIORITY_DEFAULT"></a> 106 <code class="literal">DB_PRIORITY_DEFAULT</code> 107 </p> 108 <p> 109 The default priority. 110 </p> 111 </li> 112 <li> 113 <p><a id="set_priority_DB_PRIORITY_HIGH"></a> 114 <code class="literal">DB_PRIORITY_HIGH</code> 115 </p> 116 <p> 117 The next highest priority. 118 </p> 119 </li> 120 <li> 121 <p><a id="set_priority_DB_PRIORITY_VERY_HIGH"></a> 122 <code class="literal">DB_PRIORITY_VERY_HIGH</code> 123 </p> 124 <p> 125 The highest priority: pages are the least likely to be discarded. 126 </p> 127 </li> 128 </ul> 129 </div> 130 </div> 131 </div> 132 <div class="sect2" lang="en" xml:lang="en"> 133 <div class="titlepage"> 134 <div> 135 <div> 136 <h3 class="title"><a id="id1649530"></a>Class</h3> 137 </div> 138 </div> 139 </div> 140 <p> 141 <a class="link" href="db.html" title="Chapter��2.�� The DB Handle">DB</a> 142 </p> 143 </div> 144 <div class="sect2" lang="en" xml:lang="en"> 145 <div class="titlepage"> 146 <div> 147 <div> 148 <h3 class="title"><a id="id1649438"></a>See Also</h3> 149 </div> 150 </div> 151 </div> 152 <p> 153 <a class="xref" href="db.html#dblist" title="Database and Related Methods">Database and Related Methods</a> 154 </p> 155 </div> 156 </div> 157 <div class="navfooter"> 158 <hr /> 159 <table width="100%" summary="Navigation footer"> 160 <tr> 161 <td width="40%" align="left"><a accesskey="p" href="dbset_partition_dirs.html">Prev</a>��</td> 162 <td width="20%" align="center"> 163 <a accesskey="u" href="db.html">Up</a> 164 </td> 165 <td width="40%" align="right">��<a accesskey="n" href="dbset_q_extentsize.html">Next</a></td> 166 </tr> 167 <tr> 168 <td width="40%" align="left" valign="top">DB->set_partition_dirs()��</td> 169 <td width="20%" align="center"> 170 <a accesskey="h" href="index.html">Home</a> 171 </td> 172 <td width="40%" align="right" valign="top">��DB->set_q_extentsize()</td> 173 </tr> 174 </table> 175 </div> 176 </body> 177</html> 178