956980971f
The old code did not't correctly add TIME_FOR_COMPARE to rows that are part of the scan that will be compared with the attached where clause. Now the cost calculation for hash join and full join cache join are identical except for HASH_FANOUT (10%) The cost for a join with keys is now also uniform. The total cost for a using a key for lookup is calculated in one place as: (cost_of_finding_rows_through_key(records) + records/TIME_FOR_COMPARE)* record_count_of_previous_row_combinations + startup_cost startup_cost is the cost of a creating a temporary table (if needed) Best_cost now includes the cost of comparing all WHERE clauses and also cost of joining with previous row combinations. Other things: - Optimizer trace is now printing the total costs, including testing the WHERE clause (TIME_FOR_COMPARE) and comparing with all previous rows. - In optimizer trace, include also total cost of query together with the final join order. This makes it easier to find out where the cost was calculated. - Old code used filter even if the cost for it was higher than not using a filter. This is not corrected. - When rebasing on 10.11, I noticed some changes to access_cost_factor calculation. These changes was not picked as the coming changes to filtering will make that code obsolete.
Code status:
ci.appveyor.com
MariaDB: The open source relational database
MariaDB was designed as a drop-in replacement of MySQL(R) with more features, new storage engines, fewer bugs, and better performance.
MariaDB is brought to you by the MariaDB Foundation and the MariaDB Corporation. Please read the CREDITS file for details about the MariaDB Foundation, and who is developing MariaDB.
MariaDB is developed by many of the original developers of MySQL who now work for the MariaDB Corporation, the MariaDB Foundation and by many people in the community.
MySQL, which is the base of MariaDB, is a product and trademark of Oracle Corporation, Inc. For a list of developers and other contributors, see the Credits appendix. You can also run 'SHOW authors' to get a list of active contributors.
A description of the MariaDB project and a manual can be found at:
https://mariadb.com/kb/en/mariadb-vs-mysql-features/
https://mariadb.com/kb/en/mariadb-versus-mysql-compatibility/
https://mariadb.com/kb/en/new-and-old-releases/
Help
More help is available from the Maria Discuss mailing list https://launchpad.net/~maria-discuss, MariaDB's Zulip instance, https://mariadb.zulipchat.com/
Live QA for beginner contributors
MariaDB has a dedicated time each week when we answer new contributor questions live on Zulip. From 8:00 to 10:00 UTC on Mondays, and 10:00 to 12:00 UTC on Thursdays, anyone can ask any questions they’d like, and a live developer will be available to assist.
New contributors can ask questions any time, but we will provide immediate feedback during that interval.
Licensing
NOTE:
MariaDB is specifically available only under version 2 of the GNU General Public License (GPLv2). (I.e. Without the "any later version" clause.) This is inherited from MySQL. Please see the README file in the MySQL distribution for more information.
License information can be found in the COPYING file. Third party license information can be found in the THIRDPARTY file.
Bug Reports
Bug and/or error reports regarding MariaDB should be submitted at: https://jira.mariadb.org
For reporting security vulnerabilities see: https://mariadb.org/about/security-policy/
The code for MariaDB, including all revision history, can be found at: https://github.com/MariaDB/server