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MariaDB server is a community developed fork of MySQL server. Started by core members of the original MySQL team, MariaDB actively works with outside developers to deliver the most featureful, stable, and sanely licensed open SQL server in the industry.
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082e0b957d
BY CACHING OR REDUCING CREATEEVENT CALLS". 5.5 versions of MySQL server performed worse than 5.1 versions under single-connection workload in autocommit mode on Windows XP. Part of this slowdown can be attributed to overhead associated with constant creation/destruction of MDL_lock objects in the MDL subsystem. The problem is that creation/destruction of these objects causes creation and destruction of associated synchronization primitives, which are expensive on Windows XP. This patch tries to alleviate this problem by introducing a cache of unused MDL_object_lock objects. Instead of destroying such objects we put them into the cache and then reuse with a new key when creation of a new object is requested. To limit the size of this cache, a new --metadata-locks-cache-size start-up parameter was introduced. mysql-test/r/mysqld--help-notwin.result: Updated test after adding --metadata-locks-cache-size parameter. mysql-test/r/mysqld--help-win.result: Updated test after adding --metadata-locks-cache-size parameter. mysql-test/suite/sys_vars/r/metadata_locks_cache_size_basic.result: Added test coverage for newly introduced --metadata_locks_cache_size start-up parameter and corresponding global read-only variable. mysql-test/suite/sys_vars/t/metadata_locks_cache_size_basic-master.opt: Added test coverage for newly introduced --metadata_locks_cache_size start-up parameter and corresponding global read-only variable. mysql-test/suite/sys_vars/t/metadata_locks_cache_size_basic.test: Added test coverage for newly introduced --metadata_locks_cache_size start-up parameter and corresponding global read-only variable. sql/mdl.cc: Introduced caching of unused MDL_object_lock objects, in order to avoid costs associated with constant creation and destruction of such objects in single-connection workloads run in autocommit mode. Such costs can be pretty high on systems where creation and destruction of synchronization primitives require a system call (e.g. Windows XP). To implement this cache,a list of unused MDL_object_lock instances was added to MDL_map object. Instead of being destroyed MDL_object_lock instances are put into this list and re-used later when creation of a new instance is required. Also added MDL_lock::m_version counter to allow threads having outstanding references to an MDL_object_lock instance to notice that it has been moved to the unused objects list. Added a global variable for a start-up parameter that limits the size of the unused objects list. Note that we don't cache MDL_scoped_lock objects since they are supposed to be created only during execution of DDL statements and therefore should not affect performance much. sql/mdl.h: Added a global variable for start-up parameter that limits the size of the unused MDL_object_lock objects list and constant for its default value. sql/sql_plist.h: Added I_P_List<>::pop_front() function. sql/sys_vars.cc: Introduced --metadata-locks-cache-size start-up parameter for specifying size of the cache of unused MDL_object_lock objects. |
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| libmysql | ||
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| COPYING | ||
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| INSTALL-WIN-SOURCE | ||
| README | ||
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MySQL Server 5.5 This is a release of MySQL, a dual-license SQL database server. For the avoidance of doubt, this particular copy of the software is released under the version 2 of the GNU General Public License. MySQL is brought to you by Oracle. Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved. License information can be found in the COPYING file. MySQL FOSS License Exception We want free and open source software applications under certain licenses to be able to use specified GPL-licensed MySQL client libraries despite the fact that not all such FOSS licenses are compatible with version 2 of the GNU General Public License. Therefore there are special exceptions to the terms and conditions of the GPLv2 as applied to these client libraries, which are identified and described in more detail in the FOSS License Exception at <http://www.mysql.com/about/legal/licensing/foss-exception.html>. This distribution may include materials developed by third parties. For license and attribution notices for these materials, please refer to the documentation that accompanies this distribution (see the "Licenses for Third-Party Components" appendix) or view the online documentation at <http://dev.mysql.com/doc/>. GPLv2 Disclaimer For the avoidance of doubt, except that if any license choice other than GPL or LGPL is available it will apply instead, Oracle elects to use only the General Public License version 2 (GPLv2) at this time for any software where a choice of GPL license versions is made available with the language indicating that GPLv2 or any later version may be used, or where a choice of which version of the GPL is applied is otherwise unspecified. For further information about MySQL or additional documentation, see: - The latest information about MySQL: http://www.mysql.com - The current MySQL documentation: http://dev.mysql.com/doc Some Reference Manual sections of special interest: - If you are migrating from an older version of MySQL, please read the "Upgrading from..." section. - To see what MySQL can do, take a look at the features section. - For installation instructions, see the Installing and Upgrading chapter. - For the new features/bugfix history, see the MySQL Change History appendix. You can browse the MySQL Reference Manual online or download it in any of several formats at the URL given earlier in this file. Source distributions include a local copy of the manual in the Docs directory.