<?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>set_open_flags</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="configuration_reference.html" title="Appendix B. DB_CONFIG Parameter Reference" /> <link rel="prev" href="set_mp_mmapsize_parameter.html" title="set_mp_mmapsize" /> <link rel="next" href="set_shm_key_parameter.html" title="set_shm_key" /> </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">set_open_flags</th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="set_mp_mmapsize_parameter.html">Prev</a> </td> <th width="60%" align="center">Appendix B. DB_CONFIG Parameter Reference</th> <td width="20%" align="right"> <a accesskey="n" href="set_shm_key_parameter.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="set_open_flags_parameter"></a>set_open_flags</h2> </div> </div> </div> <p> Initializes specific subsystems of the Berkeley DB environment. </p> <p> The syntax of the entry in the <a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a> is a single line with the string <code class="literal">set_open_flags</code>, one or more whitespace characters, the method flag parameter as a string, optionally one or more whitespace characters, and the string <code class="literal">on</code> or <code class="literal">off</code>. If the optional string is omitted, the default is <code class="literal">on</code>; for example, <code class="literal">set_open_flags DB_INIT_REP</code> or <code class="literal">set_open_flags DB_INIT_REP on</code>. Because the DB_CONFIG file is read when the database environment is opened, it will silently overrule configuration done before that time. </p> <p> The method flag parameters are as follows: </p> <div class="itemizedlist"> <ul type="disc"> <li> DB_INIT_REP <p> Enables/disables DB_INIT_REP in the DB_ENV->open method. For example: </p><pre class="programlisting">set_open_flags DB_INIT_REP on</pre><p> This enables initializing the replication subsystem. This subsystem should be used whenever an application plans on using replication. This setting overwrites the DB_INIT_REP flag passed from the application's DB_ENV->open method. </p></li> <li> DB_PRIVATE <p> Enables/disables DB_PRIVATE in the DB_ENV->open method. For example: </p><pre class="programlisting">set_open_flags DB_PRIVATE on</pre><p> This enables region memory allocation from the heap instead of from memory backed by the filesystem or system shared memory. This flag implies the environment will only be accessed by a single process (although that process may be multithreaded). This flag has two effects on the Berkeley DB environment. First, all underlying data structures are allocated from per-process memory instead of from shared memory that is accessible to more than a single process. Second, mutexes are only configured to work between threads. This setting overwrites the DB_PRIVATE flag passed from the application's DB_ENV->open method. </p></li> <li> DB_THREAD <p> Enables/disables DB_THREAD in the DB_ENV->open method. For example: </p><pre class="programlisting">set_open_flags DB_THREAD on</pre><p>This enables the DB_ENV handle returned by the DB_ENV->open method to be free-threaded; that is, concurrently usable by multiple threads in the address space. This setting overwrites the DB_THREAD flag passed from the application's DB_ENV->open method.</p></li> </ul> </div> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="set_mp_mmapsize_parameter.html">Prev</a> </td> <td width="20%" align="center"> <a accesskey="u" href="configuration_reference.html">Up</a> </td> <td width="40%" align="right"> <a accesskey="n" href="set_shm_key_parameter.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">set_mp_mmapsize </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> set_shm_key</td> </tr> </table> </div> </body> </html>