mirror of
https://github.com/MariaDB/server.git
synced 2025-01-20 22:12:30 +01:00
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.
amazon-web-servicesdatabasefulltext-searchgalerageographical-information-systeminnodbjsonmariadbmysqlrdbmsrelational-databasessqlstorage-enginevector-database
ea4de078af
FOR CERTAIN QUERIES TO INFORMATION_SCHEMA". The problem was that metadata locking subsystem introduced too much overhead for queries to I_S which were processed by opening only .FRM or .TRG files and had to scanned a lot of tables (e.g. SELECT COUNT(*) FROM I_S.TRIGGERS was affected). The same effect was not observed for similar queries which performed full-blown table open in order to fill I_S table. The problem stemmed from the fact that in case when I_S implementation opened only .FRM or .TRG file for each table processed it didn't release metadata lock it has acquired on the table after finishing its processing. As result, list of acquired metadata locks were growing until the end of statement. Since acquisition of each new lock required search in the list of already acquired locks performance degraded. The same effect is not observed when I_S implementation performs full-blown table open for each table being processed, as in the latter cases metadata lock on the table is released right after table processing. This fix addressed the problem by ensuring that I_S implementation releases metadata lock after processing the table in both cases of full-blown table open and in case when only .FRM or .TRG file is read. mysql-test/r/information_schema.result: Added coverage for bug #12828477 - "MDL SUBSYSTEM CREATES BIG OVERHEAD FOR CERTAIN QUERIES TO INFORMATION_SCHEMA". mysql-test/t/information_schema.test: Added coverage for bug #12828477 - "MDL SUBSYSTEM CREATES BIG OVERHEAD FOR CERTAIN QUERIES TO INFORMATION_SCHEMA". sql/sql_show.cc: Changed fill_schema_table_from_frm() to release metadata lock it has acquired after processing the .FRM or .TRG file for table. Without this step metadata locks acquired for each table processed will be accumulated. In situation when a lot of tables are processed by I_S query this will result in transaction with too many metadata locks. As result performance of acquisition of new lock will degrade. |
||
|---|---|---|
| .bzr-mysql | ||
| BUILD | ||
| client | ||
| cmake | ||
| cmd-line-utils | ||
| dbug | ||
| Docs | ||
| extra | ||
| include | ||
| libmysql | ||
| libmysqld | ||
| libservices | ||
| man | ||
| mysql-test | ||
| mysys | ||
| packaging/WiX | ||
| plugin | ||
| regex | ||
| scripts | ||
| sql | ||
| sql-bench | ||
| sql-common | ||
| storage | ||
| strings | ||
| support-files | ||
| tests | ||
| unittest | ||
| vio | ||
| win | ||
| zlib | ||
| .bzrignore | ||
| BUILD-CMAKE | ||
| CMakeLists.txt | ||
| config.h.cmake | ||
| configure.cmake | ||
| COPYING | ||
| INSTALL-SOURCE | ||
| INSTALL-WIN-SOURCE | ||
| README | ||
| VERSION | ||
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.