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::upgrade()</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="dbtruncate.html" title="Db::truncate()" /> 12 <link rel="next" href="dbverify.html" title="Db::verify()" /> 13 </head> 14 <body> 15 <div class="navheader"> 16 <table width="100%" summary="Navigation header"> 17 <tr> 18 <th colspan="3" align="center">Db::upgrade()</th> 19 </tr> 20 <tr> 21 <td width="20%" align="left"><a accesskey="p" href="dbtruncate.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="dbverify.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="dbupgrade"></a>Db::upgrade()</h2> 35 </div> 36 </div> 37 </div> 38 <pre class="programlisting">#include <db_cxx.h> 39 40int 41Db::upgrade(const char *file, u_int32_t flags);</pre> 42 <p> 43 The <code class="methodname">Db::upgrade()</code> method upgrades all of the databases included in 44 the file <span class="bold"><strong>file</strong></span>, if necessary. If no 45 upgrade is necessary, <code class="methodname">Db::upgrade()</code> always returns success. 46 </p> 47 <p> 48 <span class="bold"><strong>Database upgrades are done in place and are 49 destructive. For example, if pages need to be allocated and no disk 50 space is available, the database may be left corrupted. Backups 51 should be made before databases are upgraded. See <a href="../../programmer_reference/am_upgrade.html" class="olink">Upgrading databases</a> for more 52 information.</strong></span> 53 </p> 54 <p> 55 Unlike all other database operations, <code class="methodname">Db::upgrade()</code> may only be done 56 on a system with the same byte-order as the database. 57 </p> 58 <p> 59 The <code class="methodname">Db::upgrade()</code> <span> 60 61 <span> 62 method either returns a non-zero error value or throws an 63 exception that encapsulates a non-zero error value on 64 failure, and returns 0 on success. 65 </span> 66 </span> 67 </p> 68 <div class="sect2" lang="en" xml:lang="en"> 69 <div class="titlepage"> 70 <div> 71 <div> 72 <h3 class="title"><a id="id1653469"></a>Parameters</h3> 73 </div> 74 </div> 75 </div> 76 <div class="sect3" lang="en" xml:lang="en"> 77 <div class="titlepage"> 78 <div> 79 <div> 80 <h4 class="title"><a id="id1653666"></a>file</h4> 81 </div> 82 </div> 83 </div> 84 <p> 85 The <span class="bold"><strong>file</strong></span> parameter is the physical 86 file containing the databases to be upgraded. 87 </p> 88 </div> 89 <div class="sect3" lang="en" xml:lang="en"> 90 <div class="titlepage"> 91 <div> 92 <div> 93 <h4 class="title"><a id="id1653652"></a>flags</h4> 94 </div> 95 </div> 96 </div> 97 <p> 98 The <span class="bold"><strong>flags</strong></span> parameter must be set to 0 99 or the following value: 100 </p> 101 <div class="itemizedlist"> 102 <ul type="disc"> 103 <li> 104 <p><a id="upgrade_DB_DUPSORT"></a> 105 <code class="literal">DB_DUPSORT</code> 106 </p> 107 <p> 108 <span class="bold"><strong>This flag is only meaningful when upgrading 109 databases from releases before the Berkeley DB 3.1 release.</strong></span> 110 </p> 111 <p> 112 As part of the upgrade from the Berkeley DB 3.0 release to the 3.1 113 release, the on-disk format of duplicate data items changed. To 114 correctly upgrade the format requires applications to specify whether 115 duplicate data items in the database are sorted or not. Specifying 116 the DB_DUPSORT flag informs <code class="methodname">Db::upgrade()</code> that the duplicates are 117 sorted; otherwise they are assumed to be unsorted. Incorrectly 118 specifying the value of this flag may lead to database corruption. 119 </p> 120 <p> 121 Further, because the <code class="methodname">Db::upgrade()</code> method upgrades a physical file 122 (including all the databases it contains), it is not possible to use 123 <code class="methodname">Db::upgrade()</code> to upgrade files in which some of the databases it 124 includes have sorted duplicate data items, and some of the databases 125 it includes have unsorted duplicate data items. If the file does not 126 have more than a single database, if the databases do not support 127 duplicate data items, or if all of the databases that support 128 duplicate data items support the same style of duplicates (either 129 sorted or unsorted), <code class="methodname">Db::upgrade()</code> will work correctly as long as the 130 DB_DUPSORT flag is correctly specified. Otherwise, the file cannot be 131 upgraded using <code class="methodname">Db::upgrade;()</code> it must be upgraded manually by dumping 132 and reloading the databases. 133 </p> 134 </li> 135 </ul> 136 </div> 137 </div> 138 </div> 139 <div class="sect2" lang="en" xml:lang="en"> 140 <div class="titlepage"> 141 <div> 142 <div> 143 <h3 class="title"><a id="id1653943"></a>Environment Variables</h3> 144 </div> 145 </div> 146 </div> 147 <p> 148 If the database was opened within a database environment, the 149 environment variable <code class="literal">DB_HOME</code> may be used as the path of the 150 database environment home. 151 </p> 152 <p> 153 <code class="methodname">Db::upgrade()</code> is affected by any database directory specified using the 154 <a class="xref" href="envset_data_dir.html" title="DbEnv::set_data_dir()">DbEnv::set_data_dir()</a> 155 method, or by setting the "set_data_dir" string in the environment's 156 <a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a> 157 file. 158 </p> 159 </div> 160 <div class="sect2" lang="en" xml:lang="en"> 161 <div class="titlepage"> 162 <div> 163 <div> 164 <h3 class="title"><a id="id1653948"></a>Errors</h3> 165 </div> 166 </div> 167 </div> 168 <p> 169 The <code class="methodname">Db::upgrade()</code> <span> 170 171 <span> 172 method may fail and throw a <a class="link" href="dbexception.html" title="Chapter 6. The DbException Class">DbException</a> 173 exception, encapsulating one of the following non-zero errors, or return one 174 of the following non-zero errors: 175 </span> 176 </span> 177 </p> 178 <div class="sect3" lang="en" xml:lang="en"> 179 <div class="titlepage"> 180 <div> 181 <div> 182 <h4 class="title"><a id="id1653951"></a>DB_OLD_VERSION</h4> 183 </div> 184 </div> 185 </div> 186 <p> 187 The database cannot be upgraded by this version of the Berkeley DB 188 software. 189 </p> 190 </div> 191 </div> 192 <div class="sect2" lang="en" xml:lang="en"> 193 <div class="titlepage"> 194 <div> 195 <div> 196 <h3 class="title"><a id="id1653657"></a>Class</h3> 197 </div> 198 </div> 199 </div> 200 <p> 201 <a class="link" href="db.html" title="Chapter 2. The Db Handle">Db</a> 202 </p> 203 </div> 204 <div class="sect2" lang="en" xml:lang="en"> 205 <div class="titlepage"> 206 <div> 207 <div> 208 <h3 class="title"><a id="id1653723"></a>See Also</h3> 209 </div> 210 </div> 211 </div> 212 <p> 213 <a class="xref" href="db.html#dblist" title="Database and Related Methods">Database and Related Methods</a> 214 </p> 215 </div> 216 </div> 217 <div class="navfooter"> 218 <hr /> 219 <table width="100%" summary="Navigation footer"> 220 <tr> 221 <td width="40%" align="left"><a accesskey="p" href="dbtruncate.html">Prev</a> </td> 222 <td width="20%" align="center"> 223 <a accesskey="u" href="db.html">Up</a> 224 </td> 225 <td width="40%" align="right"> <a accesskey="n" href="dbverify.html">Next</a></td> 226 </tr> 227 <tr> 228 <td width="40%" align="left" valign="top">Db::truncate() </td> 229 <td width="20%" align="center"> 230 <a accesskey="h" href="index.html">Home</a> 231 </td> 232 <td width="40%" align="right" valign="top"> Db::verify()</td> 233 </tr> 234 </table> 235 </div> 236 </body> 237</html> 238