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116 lines
5.6 KiB
HTML
116 lines
5.6 KiB
HTML
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<?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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<html xmlns="http://www.w3.org/1999/xhtml">
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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>set_open_flags</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="configuration_reference.html" title="Appendix D. DB_CONFIG Parameter Reference" />
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<link rel="prev" href="set_mp_mmapsize_parameter.html" title="set_mp_mmapsize" />
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<link rel="next" href="set_shm_key_parameter.html" title="set_shm_key" />
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</head>
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<body>
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<div xmlns="" class="navheader">
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<div class="libver">
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<p>Library Version 11.2.5.2</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">set_open_flags</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="set_mp_mmapsize_parameter.html">Prev</a> </td>
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<th width="60%" align="center">Appendix D. DB_CONFIG Parameter Reference</th>
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<td width="20%" align="right"> <a accesskey="n" href="set_shm_key_parameter.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="set_open_flags_parameter"></a>set_open_flags</h2>
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</div>
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</div>
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</div>
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<p>
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Initializes specific subsystems of the Berkeley DB environment.
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</p>
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<p>
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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
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with the string <code class="literal">set_open_flags</code>, one or
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more whitespace characters, the method flag parameter as a
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string, optionally one or more whitespace characters, and
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the string <code class="literal">on</code> or <code class="literal">off</code>.
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If the optional string is omitted, the default is
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<code class="literal">on</code>; for example,
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<code class="literal">set_open_flags DB_INIT_REP</code> or
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<code class="literal">set_open_flags DB_INIT_REP on</code>. Because
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the DB_CONFIG file is read when the database environment is
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opened, it will silently overrule configuration done before
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that time.
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</p>
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<p>
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The method flag parameters are as follows:
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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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DB_INIT_REP
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<p>
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Enables/disables DB_INIT_REP in the DB_ENV->open method. For example:
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</p><pre class="programlisting">set_open_flags DB_INIT_REP on</pre><p>
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This enables initializing the replication subsystem. This
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subsystem should be used whenever an application plans on
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using replication. This setting overwrites the DB_INIT_REP
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flag passed from the application's DB_ENV->open
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method.
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</p></li>
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<li>
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DB_PRIVATE
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<p>
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Enables/disables DB_PRIVATE in the DB_ENV->open method. For example:
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</p><pre class="programlisting">set_open_flags DB_PRIVATE on</pre><p>
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This enables region memory allocation from the heap instead of from memory backed by the filesystem or
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system shared memory.
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This flag implies the environment will only be accessed by a single process (although that
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process may be multithreaded). This flag has two effects on the Berkeley DB environment.
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First, all underlying data structures are allocated from per-process memory instead of from
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shared memory that is accessible to more than a single process. Second, mutexes are only
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configured to work between threads.
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This setting overwrites the DB_PRIVATE flag passed from the application's DB_ENV->open method.
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</p></li>
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<li>
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DB_THREAD
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<p>
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Enables/disables DB_THREAD in the DB_ENV->open method. For example:
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</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.
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This setting overwrites the DB_THREAD flag passed from the application's DB_ENV->open method.</p></li>
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</ul>
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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="set_mp_mmapsize_parameter.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="configuration_reference.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="set_shm_key_parameter.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">set_mp_mmapsize </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"> set_shm_key</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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