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Yasuhiro KIMURA
362 lines
14 KiB
HTML
362 lines
14 KiB
HTML
<?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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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
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<title>DbEnv::backup()</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="env.html" title="Chapter 5. The DbEnv Handle" />
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<link rel="prev" href="envadd_data_dir.html" title="DbEnv::add_data_dir()" />
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<div xmlns="" class="navheader">
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<div class="libver">
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<p>Library Version 18.1.40</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">
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<span xmlns="http://www.w3.org/1999/xhtml">DbEnv::backup()</span>
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</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="envadd_data_dir.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 5.
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The DbEnv Handle
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</th>
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<td width="20%" align="right"> <a accesskey="n" href="envclose.html">Next</a></td>
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</tr>
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</table>
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<hr />
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</div>
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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="envbackup"></a>
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<span>DbEnv::backup()</span>
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</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_cxx.h>
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int
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DbEnv::backup(const char *target, u_int32_t flags);</pre>
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<p>
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The <code class="methodname">DbEnv::backup()</code> method performs a hot
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backup of the open environment. All files used by the environment
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are backed up, so long as the normal rules for file placement are
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followed. For information on how files are normally placed relative
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to the environment directory, see
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<a href="../../programmer_reference/env_naming.html" class="olink">Berkeley DB File Naming</a> in the <em class="citetitle">Berkeley DB Programmer's Reference Guide</em>.
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</p>
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<p>
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By default, data directories and the log directory specified
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relative to the home directory will be recreated relative to the
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target directory. If absolute path names are used, then specify
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<code class="literal">DB_BACKUP_SINGLE_DIR</code> to the <code class="literal">flags</code>
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parameter.
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</p>
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<p>
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This method provides the same functionality as the
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<a class="xref" href="db_hotbackup.html" title="db_hotbackup">db_hotbackup</a>
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utility. However, this method does not perform the housekeeping
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actions performed by the <code class="literal">db_hotbackup</code> utility.
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In particular, you may want to run a checkpoint before calling this
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method. To run a checkpoint, use the
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<a class="xref" href="txncheckpoint.html" title="DbEnv::txn_checkpoint()">
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<span>DbEnv::txn_checkpoint()</span>
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</a>
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method. For more information on checkpoints, see
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<a href="../../programmer_reference/transapp_checkpoint.html" class="olink">Checkpoints</a> in the <em class="citetitle">Berkeley DB Programmer's Reference Guide</em>.
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</p>
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<p>
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To back up a single database file contained within the environment,
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use the
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<a class="xref" href="envdbbackup.html" title="DbEnv::dbbackup()">
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<span>DbEnv::dbbackup()</span>
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</a>
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method.
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</p>
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<p>
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This method's default behavior can be changed by setting backup
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callbacks. See
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<a class="xref" href="envset_backup_callbacks.html" title="DbEnv::set_backup_callbacks()">
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<span>DbEnv::set_backup_callbacks()</span>
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</a>
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for more information. Additional tuning parameters can also be set
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using the
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<a class="xref" href="envset_backup_config.html" title="DbEnv::set_backup_config()">
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<span>DbEnv::set_backup_config()</span>
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</a> method.
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</p>
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<p>
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The <code class="methodname">DbEnv::backup()</code> method may only be
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called after the environment handle has been opened.
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</p>
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<p>
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The <code class="methodname">DbEnv::backup()</code> <span>
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<span>
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method either returns a non-zero error value or throws an
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exception that encapsulates a non-zero error value on
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failure, and returns 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="idm139755616482720"></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="idm139755616481568"></a>target</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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Identifies the directory in which the back up will be
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placed. Any subdirectories required to contain the backup
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must be placed relative to this directory. Note that if
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the backup callbacks are set, then the value specified to
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this parameter is passed on to the <code class="literal">open_func()</code>
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callback. If this parameter is NULL, then the target must
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be specified to the <code class="literal">open_func()</code>
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callback.
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</p>
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<p>
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This directory, and any required subdirectories, will be
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created for you if you specify the
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<code class="literal">DB_CREATE</code> flag on the call to this
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method. Otherwise, if the target does not exist, this
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method exits with an <code class="literal">ENOENT</code>
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error return.
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</p>
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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="idm139755616490496"></a>flags</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>flags</strong></span> parameter must
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be set to 0 or by bitwise inclusively
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<span class="bold"><strong>OR</strong></span>'ing together one or more of
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the 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_BACKUP_CLEAN</code>
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</p>
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<p>
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Before performing the backup, first remove all
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files from the target backup directory tree.
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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_BACKUP_DEEP_COPY</code>
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</p>
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<p>
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Copy databases in any sub-directories in the
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environment home and any supplied data directories.
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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_BACKUP_FILES</code>
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</p>
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<p>
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Back up all ordinary files that might exist in the
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environment, and the environment's subdirectories.
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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_BACKUP_NO_LOGS</code>
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</p>
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<p>
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Back up only the <code class="literal">*.db</code>
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files. Do not backup the log files.
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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_BACKUP_SINGLE_DIR</code>
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</p>
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<p>
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Regardless of the directory structure used by the
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source environment, place all back up files in the
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single directory identified by the
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<code class="literal">target</code> parameter. Use this
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option if absolute path names to your environment
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directory and the files within that directory are
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required by your application.
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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_BACKUP_UPDATE</code>
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</p>
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<p>
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Perform an incremental back up, instead of a full
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back up. When this option is specified, only log
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files are copied to the target directory.
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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_CREATE</code>
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</p>
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<p>
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If the target directory does not exist, create it
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and any required subdirectories.
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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_EXCL</code>
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</p>
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<p>
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Return an <code class="literal">EEXIST</code> error if a
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target backup file already exists.
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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="idm139755616442896"></a>Errors</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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The <code class="methodname">DbEnv::backup()</code> <span>
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<span>
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method may fail and throw a <a class="link" href="dbexception.html" title="Chapter 6. The DbException Class">DbException</a>
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exception, encapsulating one of the following non-zero errors, or return one
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of the following non-zero errors:
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</span>
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</span>
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</p>
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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="idm139755616448560"></a>EEXIST</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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<code class="literal">DB_EXCL</code> was specified for the
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<code class="literal">flags</code> parameter, and an existing target
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file was discovered when attempting to back up a source
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file.
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</p>
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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="idm139755616432704"></a>ENOENT</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 target directory does not exist and <code class="literal">DB_CREATE</code>
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was not specified for the <code class="literal">flags</code>
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parameter.
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</p>
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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="idm139755616465184"></a>EINVAL</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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An invalid flag value or parameter was specified.
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</p>
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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="idm139755616461024"></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 DbEnv Handle">DbEnv</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="idm139755616473376"></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="env.html#envlist" title="Database Environments and Related Methods">Database Environments 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="envadd_data_dir.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="env.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="envclose.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">
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<span>DbEnv::add_data_dir()</span>
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</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">
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<span>DbEnv::close()</span>
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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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