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Updated: July 2014

mysqlcheck (1)


mysqlcheck - a table maintenance program


mysqlcheck [options] [db_name [tbl_name ...]]


MySQL Database System                               MYSQLCHECK(1)

     mysqlcheck - a table maintenance program

     mysqlcheck [options] [db_name [tbl_name ...]]

     The mysqlcheck client performs table maintenance: It checks,
     repairs, optimizes, or analyzes tables.

     Each table is locked and therefore unavailable to other
     sessions while it is being processed, although for check
     operations, the table is locked with a READ lock only (see
     Section 13.3.5, "LOCK TABLES and UNLOCK TABLES Syntax", for
     more information about READ and WRITE locks). Table
     maintenance operations can be time-consuming, particularly
     for large tables. If you use the --databases or
     --all-databases option to process all tables in one or more
     databases, an invocation of mysqlcheck might take a long
     time. (This is also true for mysql_upgrade because that
     program invokes mysqlcheck to check all tables and repair
     them if necessary.)

     mysqlcheck is similar in function to myisamchk, but works
     differently. The main operational difference is that
     mysqlcheck must be used when the mysqld server is running,
     whereas myisamchk should be used when it is not. The benefit
     of using mysqlcheck is that you do not have to stop the
     server to perform table maintenance.

     mysqlcheck uses the SQL statements CHECK TABLE, REPAIR
     TABLE, ANALYZE TABLE, and OPTIMIZE TABLE in a convenient way
     for the user. It determines which statements to use for the
     operation you want to perform, and then sends the statements
     to the server to be executed. For details about which
     storage engines each statement works with, see the
     descriptions for those statements in Section 13.7.2, "Table
     Maintenance Statements".

     The MyISAM storage engine supports all four maintenance
     operations, so mysqlcheck can be used to perform any of them
     on MyISAM tables. Other storage engines do not necessarily
     support all operations. In such cases, an error message is
     displayed. For example, if test.t is a MEMORY table, an
     attempt to check it produces this result:

         shell> mysqlcheck test t
         note     : The storage engine for the table doesn't support check

     If mysqlcheck is unable to repair a table, see
     Section 2.12.4, "Rebuilding or Repairing Tables or Indexes"

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     for manual table repair strategies. This will be the case,
     for example, for InnoDB tables, which can be checked with
     CHECK TABLE, but not repaired with REPAIR TABLE.


         It is best to make a backup of a table before performing
         a table repair operation; under some circumstances the
         operation might cause data loss. Possible causes include
         but are not limited to file system errors.

     There are three general ways to invoke mysqlcheck:

         shell> mysqlcheck [options] db_name [tbl_name ...]
         shell> mysqlcheck [options] --databases db_name ...
         shell> mysqlcheck [options] --all-databases

     If you do not name any tables following db_name or if you
     use the --databases or --all-databases option, entire
     databases are checked.

     mysqlcheck has a special feature compared to other client
     programs. The default behavior of checking tables (--check)
     can be changed by renaming the binary. If you want to have a
     tool that repairs tables by default, you should just make a
     copy of mysqlcheck named mysqlrepair, or make a symbolic
     link to mysqlcheck named mysqlrepair. If you invoke
     mysqlrepair, it repairs tables.

     The names shown in the following table can be used to change
     mysqlcheck default behavior.
     |Command       | Meaning               |
     |mysqlrepair   | The default option is |
     |              | --repair              |
     |mysqlanalyze  | The default option is |
     |              | --analyze             |
     |mysqloptimize | The default option is |
     |              | --optimize            |

     mysqlcheck supports the following options, which can be
     specified on the command line or in the [mysqlcheck] and
     [client] groups of an option file.  mysqlcheck also supports
     the options for processing option files described at
     Section, "Command-Line Options that Affect Option-
     File Handling".

     o   --help, -?

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         Display a help message and exit.

     o   --all-databases, -A

         Check all tables in all databases. This is the same as
         using the --databases option and naming all the
         databases on the command line.

     o   --all-in-1, -1

         Instead of issuing a statement for each table, execute a
         single statement for each database that names all the
         tables from that database to be processed.

     o   --analyze, -a

         Analyze the tables.

     o   --auto-repair

         If a checked table is corrupted, automatically fix it.
         Any necessary repairs are done after all tables have
         been checked.

     o   --bind-address=ip_address

         On a computer having multiple network interfaces, this
         option can be used to select which interface is employed
         when connecting to the MySQL server.

         This option is supported only in the version of
         mysqlcheck that is supplied with MySQL Cluster. It is
         not available in standard MySQL Server 5.5 releases.

     o   --character-sets-dir=path

         The directory where character sets are installed. See
         Section 10.5, "Character Set Configuration".

     o   --check, -c

         Check the tables for errors. This is the default

     o   --check-only-changed, -C

         Check only tables that have changed since the last check
         or that have not been closed properly.

     o   --check-upgrade, -g

         Invoke CHECK TABLE with the FOR UPGRADE option to check

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         tables for incompatibilities with the current version of
         the server. This option automatically enables the
         --fix-db-names and --fix-table-names options.

     o   --compress

         Compress all information sent between the client and the
         server if both support compression.

     o   --databases, -B

         Process all tables in the named databases. Normally,
         mysqlcheck treats the first name argument on the command
         line as a database name and following names as table
         names. With this option, it treats all name arguments as
         database names.

     o   --debug[=debug_options], -# [debug_options]

         Write a debugging log. A typical debug_options string is
         'd:t:o,file_name'. The default is 'd:t:o'.

     o   --debug-check

         Print some debugging information when the program exits.

     o   --debug-info

         Print debugging information and memory and CPU usage
         statistics when the program exits.

     o   --default-character-set=charset_name

         Use charset_name as the default character set. See
         Section 10.5, "Character Set Configuration".

     o   --extended, -e

         If you are using this option to check tables, it ensures
         that they are 100% consistent but takes a long time.

         If you are using this option to repair tables, it runs
         an extended repair that may not only take a long time to
         execute, but may produce a lot of garbage rows also!

     o   --default-auth=plugin

         The client-side authentication plugin to use. See
         Section 6.3.6, "Pluggable Authentication".

         This option was added in MySQL 5.5.10.

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     o   --fast, -F

         Check only tables that have not been closed properly.

     o   --fix-db-names

         Convert database names to 5.1 format. Only database
         names that contain special characters are affected.

     o   --fix-table-names

         Convert table names to 5.1 format. Only table names that
         contain special characters are affected. This option
         also applies to views.

     o   --force, -f

         Continue even if an SQL error occurs.

     o   --host=host_name, -h host_name

         Connect to the MySQL server on the given host.

     o   --medium-check, -m

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

     o   --optimize, -o

         Optimize the tables.

     o   --password[=password], -p[password]

         The password to use when connecting to the server. If
         you use the short option form (-p), you cannot have a
         space between the option and the password. If you omit
         the password value following the --password or -p option
         on the command line, mysqlcheck prompts for one.

         Specifying a password on the command line should be
         considered insecure. See Section, "End-User
         Guidelines for Password Security". You can use an option
         file to avoid giving the password on the command line.

     o   --pipe, -W

         On Windows, connect to the server using a named pipe.
         This option applies only if the server supports
         named-pipe connections.

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     o   --plugin-dir=path

         The directory in which to look for plugins. It may be
         necessary to specify this option if the --default-auth
         option is used to specify an authentication plugin but
         mysqlcheck does not find it. See Section 6.3.6,
         "Pluggable Authentication".

         This option was added in MySQL 5.5.10.

     o   --port=port_num, -P port_num

         The TCP/IP port number to use for the connection.

     o   --protocol={TCP|SOCKET|PIPE|MEMORY}

         The connection protocol to use for connecting to the
         server. It is useful when the other connection
         parameters normally would cause a protocol to be used
         other than the one you want. For details on the
         permissible values, see Section 4.2.2, "Connecting to
         the MySQL Server".

     o   --quick, -q

         If you are using this option to check tables, it
         prevents the check from scanning the rows to check for
         incorrect links. This is the fastest check method.

         If you are using this option to repair tables, it tries
         to repair only the index tree. This is the fastest
         repair method.

     o   --repair, -r

         Perform a repair that can fix almost anything except
         unique keys that are not unique.

     o   --silent, -s

         Silent mode. Print only error messages.

     o   --socket=path, -S path

         For connections to localhost, the Unix socket file to
         use, or, on Windows, the name of the named pipe to use.

     o   --ssl*

         Options that begin with --ssl specify whether to connect
         to the server using SSL and indicate where to find SSL
         keys and certificates. See Section, "SSL Command

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     o   --tables

         Override the --databases or -B option. All name
         arguments following the option are regarded as table

     o   --use-frm

         For repair operations on MyISAM tables, get the table
         structure from the .frm file so that the table can be
         repaired even if the .MYI header is corrupted.

     o   --user=user_name, -u user_name

         The MySQL user name to use when connecting to the

     o   --verbose, -v

         Verbose mode. Print information about the various stages
         of program operation.

     o   --version, -V

         Display version information and exit.

     o   --write-binlog

         This option is enabled by default, so that ANALYZE
         TABLE, OPTIMIZE TABLE, and REPAIR TABLE statements
         generated by mysqlcheck are written to the binary log.
         Use --skip-write-binlog to cause NO_WRITE_TO_BINLOG to
         be added to the statements so that they are not logged.
         Use the --skip-write-binlog when these statements should
         not be sent to replication slaves or run when using the
         binary logs for recovery from backup.

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     See attributes(5) for descriptions of the following

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     |Stability      | Uncommitted              |
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     Oracle Corporation (

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