Take down the MySQL daemon (with mysqladmin shutdown).

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

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

Make a second backup of the tables.

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

Start mysqld with --log-bin. See Section 5.3.4, “The Binary Log”. If you want to find a query that crashes mysqld, you should use --log --log-bin.

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

Restore the backup.

Restart the mysqld server without --log-bin

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

If the tables are corrupted again or you can get mysqld to die with the above command, you have found reproducible bug that should be easy to fix! FTP the tables and the binary log to ftp://ftp.mysql.com/pub/mysql/upload/ and report it in our bugs database using the instructions given in Section 1.8, “How to Report Bugs or Problems”. (Please note that the /pub/mysql/upload/ FTP directory is not listable, so you'll not see what you've uploaded in your FTP client.) If you are a support customer, you can use the MySQL Customer Support Center https://support.mysql.com/ to alert the MySQL team about the problem and have it fixed as soon as possible.