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6.6.4.2 myisamchk Check Options

myisamchk supports the following options for table checking operations:

  • --check,-c

    Command-Line Format--check

    Check the table for errors. This is the default operation if you specify no option that selects an operation type explicitly.

  • --check-only-changed,-C

    Command-Line Format--check-only-changed

    Check only tables that have changed since the last check.

  • --extend-check,-e

    Command-Line Format--extend-check

    Check the table very thoroughly. This is quite slow if the table has many indexes. This option should only be used in extreme cases. Normally,myisamchk ormyisamchk --medium-check should be able to determine whether there are any errors in the table.

    If you are using--extend-check and have plenty of memory, setting thekey_buffer_size variable to a large value helps the repair operation run faster.

    See also the description of this option under table repair options.

    For a description of the output format, seeSection 6.6.4.5, “Obtaining Table Information with myisamchk”.

  • --fast,-F

    Command-Line Format--fast

    Check only tables that haven't been closed properly.

  • --force,-f

    Command-Line Format--force

    Do a repair operation automatically ifmyisamchk finds any errors in the table. The repair type is the same as that specified with the--recover or-r option.

  • --information,-i

    Command-Line Format--information

    Print informational statistics about the table that is checked.

  • --medium-check,-m

    Command-Line Format--medium-check

    Do a check that is faster than an--extend-check operation. This finds only 99.99% of all errors, which should be good enough in most cases.

  • --read-only,-T

    Command-Line Format--read-only

    Do not mark the table as checked. This is useful if you usemyisamchk to check a table that is in use by some other application that does not use locking, such asmysqld when run with external locking disabled.

  • --update-state,-U

    Command-Line Format--update-state

    Store information in the.MYI file to indicate when the table was checked and whether the table crashed. This should be used to get full benefit of the--check-only-changed option, but you shouldn't use this option if themysqld server is using the table and you are running it with external locking disabled.