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MySQL 5.5 Reference Manual
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MySQL 5.5 Reference Manual  /  ...  /  Making a Test Case If You Experience Table Corruption Making a Test Case If You Experience Table Corruption

The following procedure applies to MyISAM tables. For information about steps to take when encountering InnoDB table corruption, see Section 1.6, “How to Report Bugs or Problems”.

If you encounter corrupted MyISAM tables or if mysqld always fails after some update statements, you can test whether the issue is reproducible by doing the following:

  1. Stop the MySQL daemon with mysqladmin shutdown.

  2. Make a backup of the tables to guard against the very unlikely case that the repair does something bad.

  3. Check all tables with myisamchk -s database/*.MYI. Repair any corrupted tables with myisamchk -r database/table.MYI.

  4. Make a second backup of the tables.

  5. Remove (or move away) any old log files from the MySQL data directory if you need more space.

  6. Start mysqld with the binary log enabled. If you want to find a statement that crashes mysqld, you should start the server with the general query log enabled as well. See Section 5.4.3, “The General Query Log”, and Section 5.4.4, “The Binary Log”.

  7. When you have gotten a crashed table, stop the mysqld server.

  8. Restore the backup.

  9. Restart the mysqld server without the binary log enabled.

  10. Re-execute the statements with mysqlbinlog binary-log-file | mysql. The binary log is saved in the MySQL database directory with the name hostname-bin.NNNNNN.

  11. If the tables are corrupted again or you can get mysqld to die with the above command, you have found a reproducible bug. FTP the tables and the binary log to our bugs database using the instructions given in Section 1.6, “How to Report Bugs or Problems”. If you are a support customer, you can use the MySQL Customer Support Center ( to alert the MySQL team about the problem and have it fixed as soon as possible.

You can also use the script mysql_find_rows to just execute some of the update statements if you want to narrow down the problem.

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