MYSQLCHECK(1)

NAME
mysqlcheck - a table maintenance program

SYNOPSIS

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

DESCRIPTION

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”.

    • --help, -?
    Command-Line Format | --help

    Display a help message and exit.

    • --all-databases, -A
    Command-Line Format | --all-databases

    Check all tables in all databases. This is the same as using the --databases option and naming all the databases on the command line, except that the INFORMATION_SCHEMA and performance_schema databases are not checked. They can be checked by explicitly naming them with the --databases option.

    • --all-in-1, -1
    Command-Line Format | --all-in-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.

    • --analyze, -a
    Command-Line Format | --analyze

    Analyze the tables.

    • --auto-repair
    Command-Line Format | --auto-repair

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

    • --bind-address=ip_address
    Command-Line Format | --bind-address=ip_address

    On a computer having multiple network interfaces, use this option to select which interface to use for connecting to the MySQL server.

    • --character-sets-dir=dir_name
    Command-Line Format | --character-sets-dir=dir_name
    Type | Directory name

    The directory where character sets are installed. See Section 12.15, “Character Set Configuration”.

    • --check, -c
    Command-Line Format | --check

    Check the tables for errors. This is the default operation.

    • --check-only-changed, -C
    Command-Line Format | --check-only-changed

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

    • --check-upgrade, -g
    Command-Line Format | --check-upgrade

    Invoke CHECK TABLE with the FOR UPGRADE option to check tables for incompatibilities with the current version of the server.

    • --compress
    Command-Line Format | --compress[={OFF|ON}]
    Deprecated | 8.0.18
    Type | Boolean
    Default Value | OFF

    Compress all information sent between the client and the server if possible. See Section 6.2.8, “Connection Compression Control”.

    As of MySQL 8.0.18, this option is deprecated. Expect it to be removed in a future version of MySQL. See the section called “Configuring Legacy Connection Compression”.

    • --compression-algorithms=value
    Command-Line Format | --compression-algorithms=value
    Introduced | 8.0.18
    Type | Set
    Default Value | uncompressed
    Valid Values | zlib zstd uncompressed

    The permitted compression algorithms for connections to the server. The available algorithms are the same as for the protocol_compression_algorithms system variable. The default value is uncompressed.

    For more information, see Section 6.2.8, “Connection Compression Control”.

    This option was added in MySQL 8.0.18.

    • --databases, -B
    Command-Line Format | --databases

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

    • --debug[=debug_options], -# [debug_options]
    Command-Line Format | --debug[=debug_options]
    Type | String
    Default Value | d:t:o

    Write a debugging log. A typical debug_options string is d:t:o,file_name. The default is d:t:o.

    This option is available only if MySQL was built using WITH_DEBUG. MySQL release binaries provided by Oracle are not built using this option.

    • --debug-check
    Command-Line Format | --debug-check
    Type | Boolean
    Default Value | FALSE

    Print some debugging information when the program exits.

    This option is available only if MySQL was built using WITH_DEBUG. MySQL release binaries provided by Oracle are not built using this option.

    • --debug-info
    Command-Line Format | --debug-info
    Type | Boolean
    Default Value | FALSE

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

    This option is available only if MySQL was built using WITH_DEBUG. MySQL release binaries provided by Oracle are not built using this option.

    • --default-character-set=charset_name
    Command-Line Format | --default-character-set=charset_name
    Type | String

    Use charset_name as the default character set. See Section 12.15, “Character Set Configuration”.

    • --defaults-extra-file=file_name
    Command-Line Format | --defaults-extra-file=file_name
    Type | File name

    Read this option file after the global option file but (on Unix) before the user option file. If the file does not exist or is otherwise inaccessible, an error occurs. If file_name is not an absolute path name, it is interpreted relative to the current directory.

    For additional information about this and other option-file options, see Section 6.2.2.3, “Command-Line Options that Affect Option-File Handling”.

    • --defaults-file=file_name
    Command-Line Format | --defaults-file=file_name
    Type | File name

    Use only the given option file. If the file does not exist or is otherwise inaccessible, an error occurs. If file_name is not an absolute path name, it is interpreted relative to the current directory.

    Exception: Even with --defaults-file, client programs read .mylogin.cnf.

    For additional information about this and other option-file options, see Section 6.2.2.3, “Command-Line Options that Affect Option-File Handling”.

    • --defaults-group-suffix=str
    Command-Line Format | --defaults-group-suffix=str
    Type | String

    Read not only the usual option groups, but also groups with the usual names and a suffix of str. For example, mysqlcheck normally reads the [client] and [mysqlcheck] groups. If this option is given as --defaults-group-suffix=_other, mysqlcheck also reads the [client_other] and [mysqlcheck_other] groups.

    For additional information about this and other option-file options, see Section 6.2.2.3, “Command-Line Options that Affect Option-File Handling”.

    • --extended, -e
    Command-Line Format | --extended

    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!

    • --default-auth=plugin
    Command-Line Format | --default-auth=plugin
    Type | String

    A hint about which client-side authentication plugin to use. See Section 8.2.17, “Pluggable Authentication”.

    • --enable-cleartext-plugin
    Command-Line Format | --enable-cleartext-plugin
    Type | Boolean
    Default Value | FALSE

    Enable the mysql_clear_password cleartext authentication plugin. (See Section 8.4.1.4, “Client-Side Cleartext Pluggable Authentication”.)

    • --fast, -F
    Command-Line Format | --fast

    Check only tables that have not been closed properly.

    • --force, -f
    Command-Line Format | --force

    Continue even if an SQL error occurs.

    • --get-server-public-key
    Command-Line Format | --get-server-public-key
    Type | Boolean

    Request from the server the public key required for RSA key pair-based password exchange. This option applies to clients that authenticate with the caching_sha2_password authentication plugin. For that plugin, the server does not send the public key unless requested. This option is ignored for accounts that do not authenticate with that plugin. It is also ignored if RSA-based password exchange is not used, as is the case when the client connects to the server using a secure connection.

    If --server-public-key-path=file_name is given and specifies a valid public key file, it takes precedence over --get-server-public-key.

    For information about the caching_sha2_password plugin, see Section 8.4.1.2, “Caching SHA-2 Pluggable Authentication”.

    • --host=host_name, -h host_name
    Command-Line Format | --host=host_name
    Type | String
    Default Value | localhost

    Connect to the MySQL server on the given host.

    • --login-path=name
    Command-Line Format | --login-path=name
    Type | String

    Read options from the named login path in the .mylogin.cnf login path file. A “login path” is an option group containing options that specify which MySQL server to connect to and which account to authenticate as. To create or modify a login path file, use the mysql_config_editor utility. See mysql_config_editor(1).

    For additional information about this and other option-file options, see Section 6.2.2.3, “Command-Line Options that Affect Option-File Handling”.

    • --medium-check, -m
    Command-Line Format | --medium-check

    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.

    • --no-defaults
    Command-Line Format | --no-defaults

    Do not read any option files. If program startup fails due to reading unknown options from an option file, --no-defaults can be used to prevent them from being read.

    The exception is that the .mylogin.cnf file is read in all cases, if it exists. This permits passwords to be specified in a safer way than on the command line even when --no-defaults is used. To create .mylogin.cnf, use the mysql_config_editor utility. See mysql_config_editor(1).

    For additional information about this and other option-file options, see Section 6.2.2.3, “Command-Line Options that Affect Option-File Handling”.

    • --optimize, -o
    Command-Line Format | --optimize

    Optimize the tables.

    • --password[=password], -p[password]
    Command-Line Format | --password[=password]
    Type | String

    The password of the MySQL account used for connecting to the server. The password value is optional. If not given, mysqlcheck prompts for one. If given, there must be no space between --password= or -p and the password following it. If no password option is specified, the default is to send no password.

    Specifying a password on the command line should be considered insecure. To avoid giving the password on the command line, use an option file. See Section 8.1.2.1, “End-User Guidelines for Password Security”.

    To explicitly specify that there is no password and that mysqlcheck should not prompt for one, use the --skip-password option.

    • --password1[=pass_val] The password for multifactor authentication factor 1 of the MySQL account used for connecting to the server. The password value is optional. If not given, mysqlcheck prompts for one. If given, there must be no space between --password1= and the password following it. If no password option is specified, the default is to send no password.

    Specifying a password on the command line should be considered insecure. To avoid giving the password on the command line, use an option file. See Section 8.1.2.1, “End-User Guidelines for Password Security”.

    To explicitly specify that there is no password and that mysqlcheck should not prompt for one, use the --skip-password1 option.

    --password1 and --password are synonymous, as are --skip-password1 and --skip-password.

    • --password2[=pass_val] The password for multifactor authentication factor 2 of the MySQL account used for connecting to the server. The semantics of this option are similar to the semantics for --password1; see the description of that option for details.

    • --password3[=pass_val] The password for multifactor authentication factor 3 of the MySQL account used for connecting to the server. The semantics of this option are similar to the semantics for --password1; see the description of that option for details.

    • --pipe, -W
    Command-Line Format | --pipe
    Type | String

    On Windows, connect to the server using a named pipe. This option applies only if the server was started with the named_pipe system variable enabled to support named-pipe connections. In addition, the user making the connection must be a member of the Windows group specified by the named_pipe_full_access_group system variable.

    • --plugin-dir=dir_name
    Command-Line Format | --plugin-dir=dir_name
    Type | Directory name

    The directory in which to look for plugins. Specify this option if the --default-auth option is used to specify an authentication plugin but mysqlcheck does not find it. See Section 8.2.17, “Pluggable Authentication”.

    • --port=port_num, -P port_num
    Command-Line Format | --port=port_num
    Type | Numeric
    Default Value | 3306

    For TCP/IP connections, the port number to use.

    • --print-defaults
    Command-Line Format | --print-defaults

    Print the program name and all options that it gets from option files.

    For additional information about this and other option-file options, see Section 6.2.2.3, “Command-Line Options that Affect Option-File Handling”.

    • --protocol={TCP|SOCKET|PIPE|MEMORY}
    Command-Line Format | --protocol=type
    Type | String
    Default Value | [see text]
    Valid Values | TCP SOCKET PIPE MEMORY

    The transport protocol to use for connecting to the server. It is useful when the other connection parameters normally result in use of a protocol other than the one you want. For details on the permissible values, see Section 6.2.7, “Connection Transport Protocols”.

    • --quick, -q
    Command-Line Format | --quick

    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.

    • --repair, -r
    Command-Line Format | --repair

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

    • --server-public-key-path=file_name
    Command-Line Format | --server-public-key-path=file_name
    Type | File name

    The path name to a file in PEM format containing a client-side copy of the public key required by the server for RSA key pair-based password exchange. This option applies to clients that authenticate with the sha256_password or caching_sha2_password authentication plugin. This option is ignored for accounts that do not authenticate with one of those plugins. It is also ignored if RSA-based password exchange is not used, as is the case when the client connects to the server using a secure connection.

    If --server-public-key-path=file_name is given and specifies a valid public key file, it takes precedence over --get-server-public-key.

    For sha256_password, this option applies only if MySQL was built using OpenSSL.

    For information about the sha256_password and caching_sha2_password plugins, see Section 8.4.1.3, “SHA-256 Pluggable Authentication”, and Section 8.4.1.2, “Caching SHA-2 Pluggable Authentication”.

    • --shared-memory-base-name=name
    Command-Line Format | --shared-memory-base-name=name
    Platform Specific | Windows

    On Windows, the shared-memory name to use for connections made using shared memory to a local server. The default value is MYSQL. The shared-memory name is case-sensitive.

    This option applies only if the server was started with the shared_memory system variable enabled to support shared-memory connections.

    • --silent, -s
    Command-Line Format | --silent

    Silent mode. Print only error messages.

    • --skip-database=db_name
    Command-Line Format | --skip-database=db_name

    Do not include the named database (case-sensitive) in the operations performed by mysqlcheck.

    • --socket=path, -S path
    Command-Line Format | --socket={file_name|pipe_name}
    Type | String

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

    On Windows, this option applies only if the server was started with the named_pipe system variable enabled to support named-pipe connections. In addition, the user making the connection must be a member of the Windows group specified by the named_pipe_full_access_group system variable.

    • --ssl* Options that begin with --ssl specify whether to connect to the server using encryption and indicate where to find SSL keys and certificates. See the section called “Command Options for Encrypted Connections”.

    • --ssl-fips-mode={OFF|ON|STRICT}
    Command-Line Format | --ssl-fips-mode={OFF|ON|STRICT}
    Deprecated | 8.0.34
    Type | Enumeration
    Default Value | OFF
    Valid Values | OFF ON STRICT

    Controls whether to enable FIPS mode on the client side. The --ssl-fips-mode option differs from other --ssl-xxx options in that it is not used to establish encrypted connections, but rather to affect which cryptographic operations to permit. See Section 8.8, “FIPS Support”.

    These --ssl-fips-mode values are permitted:

        • OFF: Disable FIPS mode.

        • ON: Enable FIPS mode.

        • STRICT: Enable “strict” FIPS mode.

        Note
        If the OpenSSL FIPS Object Module is not available, the only permitted value for --ssl-fips-mode is OFF. In this case, setting --ssl-fips-mode to ON or STRICT causes the client to produce a warning at startup and to operate in non-FIPS mode.

    As of MySQL 8.0.34, this option is deprecated. Expect it to be removed in a future version of MySQL.

    • --tables
    Command-Line Format | --tables

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

    • --tls-ciphersuites=ciphersuite_list
    Command-Line Format | --tls-ciphersuites=ciphersuite_list
    Introduced | 8.0.16
    Type | String

    The permissible ciphersuites for encrypted connections that use TLSv1.3. The value is a list of one or more colon-separated ciphersuite names. The ciphersuites that can be named for this option depend on the SSL library used to compile MySQL. For details, see Section 8.3.2, “Encrypted Connection TLS Protocols and Ciphers”.

    This option was added in MySQL 8.0.16.

    • --tls-version=protocol_list
    Command-Line Format | --tls-version=protocol_list
    Type | String
    Default Value (≥ 8.0.16) | TLSv1,TLSv1.1,TLSv1.2,TLSv1.3 (OpenSSL 1.1.1 or higher) TLSv1,TLSv1.1,TLSv1.2 (otherwise)
    Default Value (≤ 8.0.15) | TLSv1,TLSv1.1,TLSv1.2

    The permissible TLS protocols for encrypted connections. The value is a list of one or more comma-separated protocol names. The protocols that can be named for this option depend on the SSL library used to compile MySQL. For details, see Section 8.3.2, “Encrypted Connection TLS Protocols and Ciphers”.

    • --use-frm
    Command-Line Format | --use-frm

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

    • --user=user_name, -u user_name
    Command-Line Format | --user=user_name,
    Type | String

    The user name of the MySQL account to use for connecting to the server.

    • --verbose, -v
    Command-Line Format | --verbose

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

    • --version, -V
    Command-Line Format | --version

    Display version information and exit.

    • --write-binlog
    Command-Line Format | --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 replicas or run when using the binary logs for recovery from backup.

    • --zstd-compression-level=level
    Command-Line Format | --zstd-compression-level=#
    Introduced | 8.0.18
    Type | Integer

    The compression level to use for connections to the server that use the zstd compression algorithm. The permitted levels are from 1 to 22, with larger values indicating increasing levels of compression. The default zstd compression level is 3. The compression level setting has no effect on connections that do not use zstd compression.

    For more information, see Section 6.2.8, “Connection Compression Control”.

    This option was added in MySQL 8.0.18.

COPYRIGHT

Copyright © 1997, 2025, Oracle and/or its affiliates.

This documentation is free software; you can redistribute it and/or modify it only under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 of the License.

This documentation is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with the program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA or see http://www.gnu.org/licenses/.

SEE ALSO
For more information, please refer to the MySQL Reference Manual, which may already be installed locally and which is also available online at http://dev.mysql.com/doc/.

AUTHOR
Oracle Corporation (http://dev.mysql.com/).