d039346a7a
Improve the performance of slave connect using B+-Tree indexes on each binlog file. The index allows fast lookup of a GTID position to the corresponding offset in the binlog file, as well as lookup of a position to find the corresponding GTID position. This eliminates a costly sequential scan of the starting binlog file to find the GTID starting position when a slave connects. This is especially costly if the binlog file is not cached in memory (IO cost), or if it is encrypted or a lot of slaves connect simultaneously (CPU cost). The size of the index files is generally less than 1% of the binlog data, so not expected to be an issue. Most of the work writing the index is done as a background task, in the binlog background thread. This minimises the performance impact on transaction commit. A simple global mutex is used to protect index reads and (background) index writes; this is fine as slave connect is a relatively infrequent operation. Here are the user-visible options and status variables. The feature is on by default and is expected to need no tuning or configuration for most users. binlog_gtid_index On by default. Can be used to disable the indexes for testing purposes. binlog_gtid_index_page_size (default 4096) Page size to use for the binlog GTID index. This is the size of the nodes in the B+-tree used internally in the index. A very small page-size (64 is the minimum) will be less efficient, but can be used to stress the BTree-code during testing. binlog_gtid_index_span_min (default 65536) Control sparseness of the binlog GTID index. If set to N, at most one index record will be added for every N bytes of binlog file written. This can be used to reduce the number of records in the index, at the cost only of having to scan a few more events in the binlog file before finding the target position Two status variables are available to monitor the use of the GTID indexes: Binlog_gtid_index_hit Binlog_gtid_index_miss The "hit" status increments for each successful lookup in a GTID index. The "miss" increments when a lookup is not possible. This indicates that the index file is missing (eg. binlog written by old server version without GTID index support), or corrupt. Signed-off-by: Kristian Nielsen <knielsen@knielsen-hq.org> |
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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