Aria storage Engine

One of the differences between MariaDB 5.1 and MySQL 5.1 is in our use of the Aria storage engine. The Aria storage engine is compiled in by default in MariaDB 5.1 and it is required to be 'in use' when mysqld is started.

Additionally, internal on-disk tables are in the Aria table format instead of the MyISAM table format. This should speed up some GROUP BY and DISTINCT queries because Aria has better caching than MyISAM.

There are also some new options to CREATE TABLE:

• TRANSACTIONAL= 0 | 1 : Transactional means crash-safe for Aria <>
• PAGE_CHECKSUM= 0 | 1 : If index and data should use page checksums for extra safety.
• TABLE_CHECKSUM= 0 | 1 : Same as CHECKSUM in MySQL 5.1
• ROW_FORMAT=PAGE : The new cacheable row format for Aria tables. Default row format for Aria tables and only row format that can be used if TRANSACTIONAL=1. To emulate MyISAM, use ROW_FORMAT=FIXED or ROW_FORMAT=DYNAMIC
• CHECKSUM TABLE now ignores values in NULL fields. This makes CHECKSUM TABLE faster and fixes some cases where same table definition could give different checksum values depending on row format. The disadvantage is that the value is now different compared to other MySQL installations. The new checksum calculation is fixed for all table engines that uses the default way to calculate and MyISAM which does the calculation internally. Note: Old MyISAM tables with internal checksum will return the same checksum as before. To fix them to calculate according to new rules you have to do an ALTER TABLE. You can use the old ways to calculate checksums by using the option --old to mysqld or set the system variable '@@old' to 1 when you do CHECKSUM TABLE ... EXTENDED;
• At startup Aria will check the Aria logs and automatically recover the tables from last checkpoint if mysqld was not taken down correctly.

See also: Aria FAQ