<?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>DbEnv::set_backup_config()</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="env.html" title="Chapter 5. The DbEnv Handle" /> <link rel="prev" href="envset_backup_callbacks.html" title="DbEnv::set_backup_callbacks()" /> <link rel="next" href="envset_data_dir.html" title="DbEnv::set_data_dir()" /> </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">DbEnv::set_backup_config()</th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="envset_backup_callbacks.html">Prev</a> </td> <th width="60%" align="center">Chapter 5. The DbEnv Handle </th> <td width="20%" align="right"> <a accesskey="n" href="envset_data_dir.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="envset_backup_config"></a>DbEnv::set_backup_config()</h2> </div> </div> </div> <pre class="programlisting">#include <db_cxx.h> DB_ENV->set_backup_config(db_backup_config_t option, u_int32_t value);</pre> <p> The <code class="methodname">DbEnv::set_backup_config()</code> method configures tuning parameters for the hot backup APIs. See the <a class="xref" href="envbackup.html" title="DbEnv::backup()">DbEnv::backup()</a> and <a class="xref" href="envdbbackup.html" title="DbEnv::dbbackup()">DbEnv::dbbackup()</a> methods for a description of the hot backup APIs. </p> <p> The <code class="methodname">DbEnv::set_backup_config()</code> method configures operations performed using the specified <a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a> handle, not all operations performed on the underlying database environment. </p> <p> The <code class="methodname">DbEnv::set_backup_config()</code> method may be called at any time during the life of the application. </p> <p> The <code class="methodname">DbEnv::set_backup_config()</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="idp1838608"></a>Parameters</h3> </div> </div> </div> <div class="sect3" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h4 class="title"><a id="idp1826664"></a>option</h4> </div> </div> </div> <p> The <span class="bold"><strong>option</strong></span> parameter identifies the backup parameter to be modified. It must be one of the following: </p> <div class="itemizedlist"> <ul type="disc"> <li> <p> <code class="literal">DB_BACKUP_WRITE_DIRECT</code> </p> <p> Turning this on causes direct I/O to be used when writing pages to the disk. For some environments, direct I/O can provide faster write throughput, but usually it is slower because the OS buffer pool offers asynchronous activity. </p> <p> By default, this option is turned off. </p> </li> <li> <p> <code class="literal">DB_BACKUP_READ_COUNT</code> </p> <p> Configures the number of pages to read before pausing. Increasing this value increases the amount of I/O the backup process performs for any given time interval. If your application is already heavily I/O bound, setting this value to a lower number may help to improve your overall data throughput by reducing the I/O demands placed on your system. </p> <p> By default, all pages are read without a pause. </p> </li> <li> <p> <code class="literal">DB_BACKUP_READ_SLEEP</code> </p> <p> Configures the number of microseconds to sleep between batches of reads. Increasing this value decreases the amount of I/O the backup process performs for any given time interval. If your application is already heavily I/O bound, setting this value to a higher number may help to improve your overall data throughput by reducing the I/O demands placed on your system. </p> </li> <li> <p> <code class="literal">DB_BACKUP_SIZE</code> </p> <p> Configures the size of the buffer, in bytes, to read from the database. Default is 1 megabyte. </p> </li> </ul> </div> </div> <div class="sect3" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h4 class="title"><a id="idp1846864"></a>value</h4> </div> </div> </div> <p> The <span class="bold"><strong>value</strong></span> parameter sets the configuration value for the option identified by the <span class="bold"><strong>option</strong></span> parameter. For those options which can only be turned on or off, this parameter should be set to <code class="literal">0</code> for off and <code class="literal">1</code> for on. Otherwise, set this parameter to an integer value that represents the number of units for which you are configuring the backup APIs. </p> </div> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="idp1828144"></a>Class</h3> </div> </div> </div> <p> <a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a>, </p> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="idp1849024"></a>See Also</h3> </div> </div> </div> <p> <a class="xref" href="env.html#envlist" title="Database Environments and Related Methods">Database Environments and Related Methods</a>, <a class="xref" href="envget_backup_config.html" title="DbEnv::get_backup_config()">DbEnv::get_backup_config()</a>, <a class="xref" href="envbackup.html" title="DbEnv::backup()">DbEnv::backup()</a>, <a class="xref" href="envdbbackup.html" title="DbEnv::dbbackup()">DbEnv::dbbackup()</a> </p> </div> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="envset_backup_callbacks.html">Prev</a> </td> <td width="20%" align="center"> <a accesskey="u" href="env.html">Up</a> </td> <td width="40%" align="right"> <a accesskey="n" href="envset_data_dir.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">DbEnv::set_backup_callbacks() </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> DbEnv::set_data_dir()</td> </tr> </table> </div> </body> </html>