MySQL 9.3 Reference Manual Including MySQL NDB Cluster 9.3

6.5.3 mysqlcheck — A Table Maintenance Program

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 15.3.6, “LOCK TABLES and UNLOCK TABLES Statements”, 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 the MySQL upgrade procedure if it determines that table checking is needed because it processes tables the same way.)

mysqlcheck must be used when the mysqld server is running, which means 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 15.7.3, “Table Maintenance Statements”.

All storage engines do not necessarily support all four maintenance operations. In such cases, an error message is displayed. For example, if test.t is an MEMORY table, an attempt to check it produces this result: 

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

If mysqlcheck is unable to repair a table, see Section 3.14, “Rebuilding or Repairing Tables or Indexes” for manual table repair strategies. This is the case, for example, for InnoDB tables, which can be checked with CHECK TABLE, but not repaired with REPAIR TABLE.

Caution

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: 

mysqlcheck [options] db_name [tbl_name ...]
mysqlcheck [options] --databases db_name ...
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. For information about option files used by MySQL programs, see Section 6.2.2.2, “Using Option Files”.

Table 6.12 mysqlcheck Options

Option Name Description
--all-databases Check all tables in all databases
--all-in-1 Execute a single statement for each database that names all the tables from that database
--analyze Analyze the tables
--auto-repair If a checked table is corrupted, automatically fix it
--bind-address Use specified network interface to connect to MySQL Server
--character-sets-dir Directory where character sets are installed
--check Check the tables for errors
--check-only-changed Check only tables that have changed since the last check
--check-upgrade Invoke CHECK TABLE with the FOR UPGRADE option
--compress Compress all information sent between client and server
--compression-algorithms Permitted compression algorithms for connections to server
--databases Interpret all arguments as database names
--debug Write debugging log
--debug-check Print debugging information when program exits
--debug-info Print debugging information, memory, and CPU statistics when program exits
--default-character-set Specify default character set
--defaults-extra-file Read named option file in addition to usual option files
--defaults-file Read only named option file
--defaults-group-suffix Option group suffix value
--enable-cleartext-plugin Enable cleartext authentication plugin
--extended Check and repair tables
--fast Check only tables that have not been closed properly
--force Continue even if an SQL error occurs
--get-server-public-key Request RSA public key from server
--help Display help message and exit
--host Host on which MySQL server is located
--login-path Read login path options from .mylogin.cnf
--medium-check Do a check that is faster than an --extended operation
--no-defaults Read no option files
--no-login-paths Do not read login paths from the login path file
--optimize Optimize the tables
--password Password to use when connecting to server
--password1 First multifactor authentication password to use when connecting to server
--password2 Second multifactor authentication password to use when connecting to server
--password3 Third multifactor authentication password to use when connecting to server
--pipe Connect to server using named pipe (Windows only)
--port TCP/IP port number for connection
--print-defaults Print default options
--protocol Transport protocol to use
--quick The fastest method of checking
--repair Perform a repair that can fix almost anything except unique keys that are not unique
--server-public-key-path Path name to file containing RSA public key
--shared-memory-base-name Shared-memory name for shared-memory connections (Windows only)
--silent Silent mode
--skip-database Omit this database from performed operations
--socket Unix socket file or Windows named pipe to use
--ssl-ca File that contains list of trusted SSL Certificate Authorities
--ssl-capath Directory that contains trusted SSL Certificate Authority certificate files
--ssl-cert File that contains X.509 certificate
--ssl-cipher Permissible ciphers for connection encryption
--ssl-fips-mode Whether to enable FIPS mode on client side
--ssl-key File that contains X.509 key
--ssl-mode Desired security state of connection to server
--ssl-session-data File that contains SSL session data
--ssl-session-data-continue-on-failed-reuse Whether to establish connections if session reuse fails
--tables Overrides the --databases or -B option
--tls-ciphersuites Permissible TLSv1.3 ciphersuites for encrypted connections
--tls-sni-servername Server name supplied by the client
--tls-version Permissible TLS protocols for encrypted connections
--use-frm For repair operations on MyISAM tables
--user MySQL user name to use when connecting to server
--verbose Verbose mode
--version Display version information and exit
--write-binlog Log ANALYZE, OPTIMIZE, REPAIR statements to binary log. --skip-write-binlog adds NO_WRITE_TO_BINLOG to these statements
--zstd-compression-level Compression level for connections to server that use zstd compression

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