The myisamchk utility gets information about your database tables or checks, repairs, or optimizes them. myisamchk works with MyISAM tables (tables that have .MYD and .MYI files for storing data and indexes).

The use of myisamchk with partitioned tables is not supported.

Invoke myisamchk like this:

shell> myisamchk [options] tbl_name ...

The options specify what you want myisamchk to do. They are described in the following sections. You can also get a list of options by invoking myisamchk --help.

With no options, myisamchk simply checks your table as the default operation. To get more information or to tell myisamchk to take corrective action, specify options as described in the following discussion.

tbl_name is the database table you want to check or repair. If you run myisamchk somewhere other than in the database directory, you must specify the path to the database directory, because myisamchk has no idea where the database is located. In fact, myisamchk does not actually care whether the files you are working on are located in a database directory. You can copy the files that correspond to a database table into some other location and perform recovery operations on them there.

You can name several tables on the myisamchk command line if you wish. You can also specify a table by naming its index file (the file with the .MYI suffix). This allows you to specify all tables in a directory by using the pattern *.MYI. For example, if you are in a database directory, you can check all the MyISAM tables in that directory like this:

shell> myisamchk *.MYI

If you are not in the database directory, you can check all the tables there by specifying the path to the directory:

shell> myisamchk /path/to/database_dir/*.MYI

You can even check all tables in all databases by specifying a wildcard with the path to the MySQL data directory:

shell> myisamchk /path/to/datadir/*/*.MYI

The recommended way to quickly check all MyISAM tables is:

shell> myisamchk --silent --fast /path/to/datadir/*/*.MYI

If you want to check all MyISAM tables and repair any that are corrupted, you can use the following command:

shell> myisamchk --silent --force --fast --update-state \
          --key_buffer_size=64M --sort_buffer_size=64M \
          --read_buffer_size=1M --write_buffer_size=1M \
          /path/to/datadir/*/*.MYI

This command assumes that you have more than 64MB free. For more information about memory allocation with myisamchk, see Section 4.6.3.6, “myisamchk Memory Usage”.

MySQL Enterprise.  For expert advice on checking and repairing tables, subscribe to the MySQL Enterprise Monitor. For more information, see http://www.mysql.com/products/enterprise/advisors.html.

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myisamchk supports the options in the following table. It also reads option files and supports the options for processing them described at Section 4.2.3.3.1, “Command-Line Options that Affect Option-File Handling”.