ea0be9e2d6
Allow ALGORITHM=INSTANT (or avoid touching any data) when changing the collation, or in some cases, the character set, of a non-indexed CHAR or VARCHAR column. There is no penalty for subsequent DDL or DML operations, and compatibility with older MariaDB versions will be unaffected. Character sets may be changed when the old encoding is compatible with the new one. For example, changing from ASCII to anything ASCII-based, or from 3-byte to 4-byte UTF-8 can sometimes be performed instantly. This is joint work with Eugene Kosov. The test cases as well as ALTER_CONVERT_TO, charsets_are_compatible(), Type_handler::Charsets_are_compatible() are his work. The Field_str::is_equal(), Field_varstring::is_equal() and the InnoDB changes were mostly rewritten by me due to conflicts with MDEV-15563. Limitations: Changes of indexed columns will still require ALGORITHM=COPY. We should allow ALGORITHM=NOCOPY and allow the indexes to be rebuilt inside the storage engine, without copying the entire table. Instant column size changes (in bytes) are not supported by all storage engines. Instant CHAR column changes are only allowed for InnoDB ROW_FORMAT=REDUNDANT. We could allow this for InnoDB when the CHAR internally uses a variable-length encoding, say, when converting from 3-byte UTF-8 to 4-byte UTF-8. Instant VARCHAR column changes are allowed for InnoDB ROW_FORMAT=REDUNDANT, and for others only if the size in bytes does not change from 128..255 bytes to more than 256 bytes. Inside InnoDB, this slightly changes the way how MDEV-15563 works and fixes the result of the innodb.instant_alter_extend test. We change the way how ALTER_COLUMN_EQUAL_PACK_LENGTH_EXT is handled. All column extension, type changes and renaming now go through a common route, except when ctx->is_instant() is in effect, for example, instant ADD or DROP COLUMN has been initiated. Only in that case we will go through innobase_instant_try() and rewrite all column metadata. get_type(field, prtype, mtype, len): Convert a SQL data type into InnoDB column metadata. innobase_rename_column_try(): Remove the update of SYS_COLUMNS. innobase_rename_or_enlarge_column_try(): New function, replacing part of innobase_rename_column_try() and all of innobase_enlarge_column_try(). Also changes column types. innobase_rename_or_enlarge_columns_cache(): Also change the column type. |
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Code status:
travis-ci.org (10.4 branch)ci.appveyor.com
MariaDB: drop-in replacement for MySQL
MariaDB is 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/library/new-and-old-releases/
As MariaDB is a full replacement of MySQL, the MySQL manual at http://dev.mysql.com/doc is generally applicable.
Help
More help is available from the Maria Discuss mailing list https://launchpad.net/~maria-discuss and the #maria IRC channel on Freenode.
Live QA for beginner contributors
MariaDB has a dedicated time each week when we answer new contributor questions live on Zulip and IRC. 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.
License
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, COPYING.LESSER, and COPYING.thirdparty files.
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/
Bugs in the MySQL code can also be submitted at: https://bugs.mysql.com
The code for MariaDB, including all revision history, can be found at: https://github.com/MariaDB/server