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143 lines
6.9 KiB
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<title>set_flags</title>
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<link rel="up" href="configuration_reference.html" title="Appendix D. DB_CONFIG Parameter Reference" />
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<div xmlns="" class="navheader">
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<div class="libver">
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<p>Library Version 11.2.5.3</p>
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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_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_create_dir_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_intermediate_dir_mode_parameter.html">Next</a></td>
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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_flags_parameter"></a>set_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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Configures a database 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> file is a single
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line with the string <code class="literal">set_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_flags DB_TXN_NOSYNC</code> or
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<code class="literal">set_flags DB_TXN_NOSYNC on</code>. Because the
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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_AUTO_COMMIT
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<p>
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Enables/disables to automatically enclose those DB handle operations for which no explicit transaction handle was specified, and
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which modify databases in the database environment, within a transaction.
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</p></li>
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<li>
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DB_CDB_ALLDB
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<p>Enables/disables Berkeley DB Concurrent Data Store applications to perform locking on an
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environment-wide basis rather than on a per-database basis.</p></li>
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<li>
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DB_DIRECT_DB
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<p>Enables/disables turning off system buffering of Berkeley DB database files to avoid double caching.</p></li>
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<li>
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DB_DSYNC_DB
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<p>Enables/disables configuring Berkeley DB to flush database writes to the backing disk before returning
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from the write system call, rather than flushing database writes explicitly in a separate
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system call, as necessary.</p></li>
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<li>
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DB_MULTIVERSION
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<p>Enables/disables all databases in the environment from being opened as if DB_MULTIVERSION is passed to
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the DB->open method. This flag will be ignored for queue databases for which
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DB_MULTIVERSION is not supported.</p></li>
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<li>
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DB_NOMMAP
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<p>Enables/disables Berkeley DB from copying read-only database files into the local cache instead of
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potentially mapping them into process memory.</p></li>
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<li>
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DB_REGION_INIT
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<p>Enables/disables Berkeley DB to page-fault shared regions into memory when initially creating or joining a Berkeley DB
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environment. In addition, Berkeley DB will write the shared regions when creating an
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environment, forcing the underlying virtual memory and filesystems to instantiate both
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the necessary memory and the necessary disk space.</p></li>
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<li>
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DB_TIME_NOTGRANTED
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<p>Enables/disables those database calls timing out based on lock or transaction timeout values to return
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DB_LOCK_NOTGRANTED instead of DB_LOCK_DEADLOCK. This allows applications to
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distinguish between operations which have deadlocked and operations which have exceeded
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their time limits.</p></li>
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<li>
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DB_TXN_NOSYNC
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<p>Enables/disables Berkeley DB to not write or synchronously flush the log on transaction commit.</p></li>
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<li>
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DB_TXN_NOWAIT
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<p>Enables/disables the operation to return DB_LOCK_DEADLOCK if a lock is unavailable for any Berkeley DB operation performed in the context of a
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transaction.</p></li>
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<li>
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DB_TXN_SNAPSHOT
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<p>Enables/disables all transactions in the environment to be started as if DB_TXN_SNAPSHOT were
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passed to the DB_ENV->txn_begin method, and all non-transactional cursors
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to be opened as if DB_TXN_SNAPSHOT were passed to the DB->cursor method.</p></li>
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<li>
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DB_TXN_WRITE_NOSYNC
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<p>Enables/disables Berkeley DB to write, but not synchronously flush, the log on transaction
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commit.</p></li>
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<li>
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DB_YIELDCPU
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<p>Enables/disables Berkeley DB to yield the processor immediately after each page or mutex acquisition.</p></li>
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</ul>
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</div>
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<p> For more information, see <a class="xref" href="envset_flags.html" title="DB_ENV->set_flags()">DB_ENV->set_flags()</a>.</p>
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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_create_dir_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_intermediate_dir_mode_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_create_dir </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_intermediate_dir_mode</td>
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</tr>
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</table>
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</body>
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