98 lines
4.4 KiB
HTML
98 lines
4.4 KiB
HTML
<!--$Id: memp_maxwrite.html 63573 2008-05-23 21:43:21Z trent.nelson $-->
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<!--Copyright (c) 1997,2008 Oracle. All rights reserved.-->
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<html>
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<head>
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<title>Berkeley DB: DbEnv::set_mp_max_write</title>
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<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit.">
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<meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++">
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</head>
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<body bgcolor=white>
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<table width="100%"><tr valign=top>
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<td>
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<b>DbEnv::set_mp_max_write</b>
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</td>
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<td align=right>
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<a href="../api_cxx/api_core.html"><img src="../images/api.gif" alt="API"></a>
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<a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a></td>
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</tr></table>
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<hr size=1 noshade>
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<tt>
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<b><pre>
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#include <db_cxx.h>
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<p>
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int
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DbEnv::set_mp_max_write(int maxwrite, db_timeout_t maxwrite_sleep);
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<p>
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int
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DbEnv::get_mp_max_write(int *maxwritep, db_timeout_t *maxwrite_sleepp);
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</pre></b>
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<hr size=1 noshade>
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<b>Description: DbEnv::set_mp_max_write</b>
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<p>The DbEnv::set_mp_max_write method limits the number of sequential write
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operations scheduled by the library when flushing dirty pages from the
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cache.</p>
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<p>The database environment's maximum number of sequential write operations may also be configured using the
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environment's <a href="../ref/env/db_config.html#DB_CONFIG">DB_CONFIG</a> file. The syntax of the entry in that
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file is a single line with the string "set_mp_max_write", one or more whitespace
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characters, and the maximum number of sequential writes and the number of microseconds
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to sleep, also separated by whitespace characters.
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Because the <a href="../ref/env/db_config.html#DB_CONFIG">DB_CONFIG</a> file is read when the database environment
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is opened, it will silently overrule configuration done before that
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time.</p>
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<p>The DbEnv::set_mp_max_write method configures a database environment, not only operations
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performed using the specified <a href="../api_cxx/env_class.html">DbEnv</a> handle.</p>
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<p>The DbEnv::set_mp_max_write method
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either returns a non-zero error value
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or throws an exception that encapsulates a non-zero error value on
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failure, and returns 0 on success.
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</p>
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<b>Parameters</b> <br>
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<b>maxwrite</b><ul compact><li>The maximum number of sequential write operations scheduled by the
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library when flushing dirty pages from the cache, or 0 if there is
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no limitation on the number of sequential write operations.</ul>
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<b>maxwrite_sleep</b><ul compact><li>The number of microseconds the thread of control should pause before
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scheduling further write operations. It must be specified as an
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unsigned 32-bit number of microseconds, limiting the maximum pause to
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roughly 71 minutes.</ul>
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<br>
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<br><b>Errors</b>
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<p>The DbEnv::set_mp_max_write method
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may fail and throw
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<a href="../api_cxx/except_class.html">DbException</a>,
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encapsulating one of the following non-zero errors, or return one of
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the following non-zero errors:</p>
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<br>
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<b>EINVAL</b><ul compact><li>An
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invalid flag value or parameter was specified.</ul>
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<br>
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<hr size=1 noshade>
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<b>Description: DbEnv::get_mp_max_write</b>
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<p>The DbEnv::get_mp_max_write method returns the current maximum number of
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sequential write operations and microseconds to pause.</p>
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<p>The DbEnv::get_mp_max_write method may be called at any time during the life of the
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application.</p>
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<p>The DbEnv::get_mp_max_write method
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either returns a non-zero error value
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or throws an exception that encapsulates a non-zero error value on
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failure, and returns 0 on success.
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</p>
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<b>Parameters</b> <br>
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<b>maxwritep</b><ul compact><li>The <b>maxwritep</b> parameter references memory into which
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the maximum number of sequential write operations is copied.</ul>
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<b>maxwrite_sleepp</b><ul compact><li>The <b>maxwrite_sleepp</b> parameter references memory into which
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the microseconds to pause before scheduling further write operations is copied.</ul>
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<br>
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<hr size=1 noshade>
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<br><b>Class</b>
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<a href="../api_cxx/env_class.html">DbEnv</a>, <a href="../api_cxx/mempfile_class.html">DbMpoolFile</a>
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<br><b>See Also</b>
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<a href="../api_cxx/memp_list.html">Memory Pools and Related Methods</a>
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</tt>
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<table width="100%"><tr><td><br></td><td align=right>
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<a href="../api_cxx/api_core.html"><img src="../images/api.gif" alt="API"></a><a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a>
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</td></tr></table>
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<p><font size=1>Copyright (c) 1996,2008 Oracle. All rights reserved.</font>
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</body>
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</html>
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