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13.5.6 Maria Statement Concurrency »
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13.5.5. Maria Usage Notes

When using Maria you should be aware of the following information and notes:

  • When using Maria tables and transactions, statements operate using the REPEATABLE READ isolation level, except when running REPAIR TABLE, OPTIMIZE TABLE, or ALTER TABLE, when all rows are exposed to all statements regardless of the isolation level.

  • When Maria is enabled, all internal on-disk temporary tables will be created using the Maria storage engine, in place of MyISAM.

  • You should not delete the maria_log_control, or the associated log files, except within the following circumstances:

    • When changing the size of the pages used in Maria data and index files.

    • If the maria_log_control gets corrupted.

    • If you want to rebuild all your Maria tables.

    Outside of these situations, deleting the maria_log_control may cause loss of data.

    If you delete maria_log_control and then want to use any existing Maria tables, you should shutdown mysqld. You can then either manually run maria_check --zerofill to check the structure and format of each Maria table, or you can wait until the first access of the table, when the check will be performed automatically. On very large tables, the check should be performed manually to ensure that there is no delay during usage.

  • If you want to copy Maria tables from one system to another, use the following sequence:

    1. Check the status of the Maria logs and ensure that the events written to the log have been applied to the tables.

    2. Shutdown the mysqld server.

    3. Copy the Maria table files. Do not copy the log files or the maria_log_control.

    4. On the new system, run maria_check --zerofill on each table that you have copied to the new system.