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_ENV->set_mp_max_write()</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="memp.html" title="Chapter��8.�� The DB_MPOOLFILE Handle" /> 11 <link rel="prev" href="mempset_mp_max_openfd.html" title="DB_ENV->set_mp_max_openfd()" /> 12 <link rel="next" href="envset_mp_mmapsize.html" title="DB_ENV->set_mp_mmapsize()" /> 13 </head> 14 <body> 15 <div class="navheader"> 16 <table width="100%" summary="Navigation header"> 17 <tr> 18 <th colspan="3" align="center">DB_ENV->set_mp_max_write()</th> 19 </tr> 20 <tr> 21 <td width="20%" align="left"><a accesskey="p" href="mempset_mp_max_openfd.html">Prev</a>��</td> 22 <th width="60%" align="center">Chapter��8.�� 23 The DB_MPOOLFILE Handle 24 </th> 25 <td width="20%" align="right">��<a accesskey="n" href="envset_mp_mmapsize.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="mempset_mp_max_write"></a>DB_ENV->set_mp_max_write()</h2> 35 </div> 36 </div> 37 </div> 38 <pre class="programlisting">#include <db.h> 39 40int 41DB_ENV->set_mp_max_write(DB_ENV *env, int maxwrite, db_timeout_t maxwrite_sleep); </pre> 42 <p> 43 The <code class="methodname">DB_ENV->set_mp_max_write()</code> method limits the number of sequential 44 write operations scheduled by the library when flushing dirty pages 45 from the cache. 46 </p> 47 <p> 48 The database environment's maximum number of sequential write 49 operations may also be configured using the environment's <a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a> file. The 50 syntax of the entry in that file is a single line with the string 51 "set_mp_max_write", one or more whitespace characters, and the maximum 52 number of sequential writes and the number of microseconds to sleep, 53 also separated by whitespace characters. Because the <a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a> file is 54 read when the database environment is opened, it will silently 55 overrule configuration done before that time. 56 </p> 57 <p> 58 The <code class="methodname">DB_ENV->set_mp_max_write()</code> method configures a database 59 environment, not only operations performed using the specified 60 <a class="link" href="env.html" title="Chapter��5.�� The DB_ENV Handle">DB_ENV</a> handle. 61 </p> 62 <p> 63 The <code class="methodname">DB_ENV->set_mp_max_write()</code> <span> 64 <span> 65 method returns a non-zero error value on failure and 0 on success. 66 </span> 67 68 </span> 69 </p> 70 <div class="sect2" lang="en" xml:lang="en"> 71 <div class="titlepage"> 72 <div> 73 <div> 74 <h3 class="title"><a id="id1688573"></a>Parameters</h3> 75 </div> 76 </div> 77 </div> 78 <div class="sect3" lang="en" xml:lang="en"> 79 <div class="titlepage"> 80 <div> 81 <div> 82 <h4 class="title"><a id="id1688741"></a>maxwrite</h4> 83 </div> 84 </div> 85 </div> 86 <p> 87 The maximum number of sequential write operations scheduled by the 88 library when flushing dirty pages from the cache, or 0 if there is no 89 limitation on the number of sequential write operations. 90 </p> 91 </div> 92 <div class="sect3" lang="en" xml:lang="en"> 93 <div class="titlepage"> 94 <div> 95 <div> 96 <h4 class="title"><a id="id1688973"></a>maxwrite_sleep</h4> 97 </div> 98 </div> 99 </div> 100 <p> 101 The number of microseconds the thread of control should pause before 102 scheduling further write operations. It must be specified as an 103 unsigned 32-bit number of microseconds, limiting the maximum pause to 104 roughly 71 minutes. 105 </p> 106 </div> 107 </div> 108 <div class="sect2" lang="en" xml:lang="en"> 109 <div class="titlepage"> 110 <div> 111 <div> 112 <h3 class="title"><a id="id1688855"></a>Errors</h3> 113 </div> 114 </div> 115 </div> 116 <p> 117 The <code class="methodname">DB_ENV->set_mp_max_write()</code> <span> 118 <span> 119 method may fail and return one of the following non-zero errors: 120 </span> 121 122 </span> 123 </p> 124 <div class="sect3" lang="en" xml:lang="en"> 125 <div class="titlepage"> 126 <div> 127 <div> 128 <h4 class="title"><a id="id1688945"></a>EINVAL</h4> 129 </div> 130 </div> 131 </div> 132 <p> 133 An invalid flag value or parameter was specified. 134 </p> 135 </div> 136 </div> 137 <div class="sect2" lang="en" xml:lang="en"> 138 <div class="titlepage"> 139 <div> 140 <div> 141 <h3 class="title"><a id="id1689013"></a>Class</h3> 142 </div> 143 </div> 144 </div> 145 <p> 146 <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> 147 </p> 148 </div> 149 <div class="sect2" lang="en" xml:lang="en"> 150 <div class="titlepage"> 151 <div> 152 <div> 153 <h3 class="title"><a id="id1689017"></a>See Also</h3> 154 </div> 155 </div> 156 </div> 157 <p> 158 <a class="xref" href="memp.html#memplist" title="Memory Pools and Related Methods">Memory Pools and Related Methods</a> 159 </p> 160 </div> 161 </div> 162 <div class="navfooter"> 163 <hr /> 164 <table width="100%" summary="Navigation footer"> 165 <tr> 166 <td width="40%" align="left"><a accesskey="p" href="mempset_mp_max_openfd.html">Prev</a>��</td> 167 <td width="20%" align="center"> 168 <a accesskey="u" href="memp.html">Up</a> 169 </td> 170 <td width="40%" align="right">��<a accesskey="n" href="envset_mp_mmapsize.html">Next</a></td> 171 </tr> 172 <tr> 173 <td width="40%" align="left" valign="top">DB_ENV->set_mp_max_openfd()��</td> 174 <td width="20%" align="center"> 175 <a accesskey="h" href="index.html">Home</a> 176 </td> 177 <td width="40%" align="right" valign="top">��DB_ENV->set_mp_mmapsize()</td> 178 </tr> 179 </table> 180 </div> 181 </body> 182</html> 183