Server System Variables QUICK Set the  MyISAM  storage engine recovery mode. The variable value is any combination of the values of OFF ,  DEFAULT ,  BACKUP ,  FORCE , or  QUICK . If you specify multiple values, separate them by commas. Specifying the variable with no value at server startup is the same as specifying  DEFAULT , and specifying with an explicit value of  ""  disables recovery (same as a value of  OFF ). If recovery is enabled, each time  mysqld  opens a  MyISAM  table, it checks whether the table is marked as crashed or was not closed properly. (The last option works only if you are running with external locking disabled.) If this is the case,  mysqld  runs a check on the table. If the table was corrupted,  mysqld  attempts to repair it. The following options affect how the repair works. Option Description OFF No recovery. DEFAULT Recovery without backup, forcing, or quick checking. BACKUP If the data file was changed during recovery, save a backup of the  tbl_name .MYD  file as tbl_name-datetime .BAK . FORCE Run recovery even if we would lose more than one row from the  .MYD  file. QUICK Do not check the rows in the table if there are not any delete blocks. Before the server automatically repairs a table, it writes a note about the repair to the error log. If you want to be able to recover from most problems without user intervention, you should use the options BACKUP,FORCE . This forces a repair of a table even if some rows would be deleted, but it keeps the old data file as a backup so that you can later examine what happened. See Section 16.2.1, “MyISAM Startup Options” . • myisam_repair_threads Command-Line Format --myisam-repair-threads=# System Variable myisam_repair_threads Scope Global, Session Dynamic Yes SET_VAR  Hint Applies No Type Integer Default Value 1 Minimum Value 1 Maximum Value (64-bit platforms) 18446744073709551615 840