It is a good idea to perform table checks on a regular basis rather than waiting for problems to occur. One way
to check and repair
MyISAM tables is with the
CHECK TABLE and
REPAIR TABLE statements. See Section
13.7.2, "Table Maintenance Statements".
Another way to check tables is to use myisamchk. For maintenance purposes, you can use myisamchk -s. The
-s option (short
causes myisamchk to run in silent mode, printing messages only when
It is also a good idea to enable automatic
MyISAM table checking. For example,
whenever the machine has done a restart in the middle of an update, you usually need to check each table that
could have been affected before it is used further. (These are "expected crashed tables.")
To cause the server to check
MyISAM tables automatically, start it with the
--myisam-recover-options option. See Section
5.1.3, "Server Command Options".
You should also check your tables regularly during normal system operation. For example, you can run a cron job to check important tables once a week, using a line like
this in a
35 0 * * 0
This prints out information about crashed tables so that you can examine and repair them as necessary.
To start with, execute myisamchk -s each night on all tables that have been updated during the last 24 hours. As you see that problems occur infrequently, you can back off the checking frequency to once a week or so.
Normally, MySQL tables need little maintenance. If you are performing many updates to
tables with dynamic-sized rows (tables with
columns) or have tables with many deleted rows you may want to defragment/reclaim space from the tables from
time to time. You can do this by using
TABLE on the tables in question. Alternatively, if you can stop the mysqld server for a while, change location into the data
directory and use this command while the server is stopped:
myisamchk -r -s --sort-index --myisam_sort_buffer_size=16M */*.MYI