<!--$Id: memp_maxwrite.so,v 10.6 2007/11/08 16:28:12 bostic Exp $--> <!--Copyright (c) 1997,2008 Oracle. All rights reserved.--> <!--See the file LICENSE for redistribution information.--> <html> <head> <title>Berkeley DB: DbEnv::set_mp_max_write</title> <meta name="description" content="Berkeley DB: An embedded database programmatic toolkit."> <meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++"> </head> <body bgcolor=white> <table width="100%"><tr valign=top> <td> <b>DbEnv::set_mp_max_write</b> </td> <td align=right> <a href="../../db47-devel-4.7.25/api_cxx/api_core.html"><img src="../../db47-devel-4.7.25/images/api.gif" alt="API"></a> <a href="../../db47-devel-4.7.25/ref/toc.html"><img src="../../db47-devel-4.7.25/images/ref.gif" alt="Ref"></a></td> </tr></table> <hr size=1 noshade> <tt> <b><pre> #include <db_cxx.h> <p> int DbEnv::set_mp_max_write(int maxwrite, db_timeout_t maxwrite_sleep); <p> int DbEnv::get_mp_max_write(int *maxwritep, db_timeout_t *maxwrite_sleepp); </pre></b> <hr size=1 noshade> <b>Description: DbEnv::set_mp_max_write</b> <p>The DbEnv::set_mp_max_write method limits the number of sequential write operations scheduled by the library when flushing dirty pages from the cache.</p> <p>The database environment's maximum number of sequential write operations may also be configured using the environment's <a href="../../db47-devel-4.7.25/ref/env/db_config.html#DB_CONFIG">DB_CONFIG</a> file. The syntax of the entry in that file is a single line with the string "set_mp_max_write", one or more whitespace characters, and the maximum number of sequential writes and the number of microseconds to sleep, also separated by whitespace characters. Because the <a href="../../db47-devel-4.7.25/ref/env/db_config.html#DB_CONFIG">DB_CONFIG</a> file is read when the database environment is opened, it will silently overrule configuration done before that time.</p> <p>The DbEnv::set_mp_max_write method configures a database environment, not only operations performed using the specified <a href="../../db47-devel-4.7.25/api_cxx/env_class.html">DbEnv</a> handle.</p> <p>The DbEnv::set_mp_max_write 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. </p> <b>Parameters</b> <br> <b>maxwrite</b><ul compact><li>The maximum number of sequential write operations scheduled by the library when flushing dirty pages from the cache, or 0 if there is no limitation on the number of sequential write operations.</ul> <b>maxwrite_sleep</b><ul compact><li>The number of microseconds the thread of control should pause before scheduling further write operations. It must be specified as an unsigned 32-bit number of microseconds, limiting the maximum pause to roughly 71 minutes.</ul> <br> <br><b>Errors</b> <p>The DbEnv::set_mp_max_write method may fail and throw <a href="../../db47-devel-4.7.25/api_cxx/except_class.html">DbException</a>, encapsulating one of the following non-zero errors, or return one of the following non-zero errors:</p> <br> <b>EINVAL</b><ul compact><li>An invalid flag value or parameter was specified.</ul> <br> <hr size=1 noshade> <b>Description: DbEnv::get_mp_max_write</b> <p>The DbEnv::get_mp_max_write method returns the current maximum number of sequential write operations and microseconds to pause.</p> <p>The DbEnv::get_mp_max_write method may be called at any time during the life of the application.</p> <p>The DbEnv::get_mp_max_write 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. </p> <b>Parameters</b> <br> <b>maxwritep</b><ul compact><li>The <b>maxwritep</b> parameter references memory into which the maximum number of sequential write operations is copied.</ul> <b>maxwrite_sleepp</b><ul compact><li>The <b>maxwrite_sleepp</b> parameter references memory into which the microseconds to pause before scheduling further write operations is copied.</ul> <br> <hr size=1 noshade> <br><b>Class</b> <a href="../../db47-devel-4.7.25/api_cxx/env_class.html">DbEnv</a>, <a href="../../db47-devel-4.7.25/api_cxx/mempfile_class.html">DbMpoolFile</a> <br><b>See Also</b> <a href="../../db47-devel-4.7.25/api_cxx/memp_list.html">Memory Pools and Related Methods</a> </tt> <table width="100%"><tr><td><br></td><td align=right> <a href="../../db47-devel-4.7.25/api_cxx/api_core.html"><img src="../../db47-devel-4.7.25/images/api.gif" alt="API"></a><a href="../../db47-devel-4.7.25/ref/toc.html"><img src="../../db47-devel-4.7.25/images/ref.gif" alt="Ref"></a> </td></tr></table> <p><font size=1>Copyright (c) 1996,2008 Oracle. All rights reserved.</font> </body> </html>