b8f9f796ff
Compute binlog checksums (when enabled) already when writing events into the statement or transaction caches, where before it was done when the caches are copied to the real binlog file. This moves the checksum computation outside of holding LOCK_log, improving scalabitily. At stmt/trx cache write time, the final end_log_pos values are not known, so with this patch these will be set to 0. Events that are written directly to the binlog file (not through stmt/trx cache) keep the correct end_log_pos value. The GTID and COMMIT/XID events at the start and end of event groups are written directly, so the zero end_log_pos is only for events in the middle of event groups, which do not negatively affect replication. An option --binlog-legacy-event-pos, off by default, is provided to disable this behavior to provide backwards compatibility with any external applications that might rely on end_log_pos in events in the middle of event groups. Checksums cannot be pre-computed when binlog encryption is enabled, as encryption relies on correct end_log_pos to provide part of the nonce/IV. Checksum pre-computation is also disabled for WSREP/Galera, as it uses events differently in its write-sets and so on. Extending pre-computation of checksums to Galera where it makes sense could be added in a future patch. The current --binlog-checksum configuration is saved in binlog_cache_data at transaction start and used to pre-compute checksums in cache, if applicable. When the cache is later copied to the binlog, a check is made if the saved value still matches the configured global value; if so, the events are block-copied directly into the binlog file. If --binlog-checksum was changed during the transaction, events are re-written to the binlog file one-by-one and the checksums recomputed/discarded as appropriate. Reviewed-by: Monty <monty@mariadb.org> Signed-off-by: Kristian Nielsen <knielsen@knielsen-hq.org>
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 our security-policy.
The code for MariaDB, including all revision history, can be found at: https://github.com/MariaDB/server