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

• --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	Yes
  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”.

  This option is deprecated. Expect it to be removed in a future version of MySQL. See Configuring Legacy Connection Compression.

• --compression-algorithms=value

  Command-Line Format	--compression-algorithms=value
  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”.

• --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 8.4.1.3, “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 8.4.1.1, “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 Section 6.6.7, “mysql_config_editor — MySQL Configuration Utility”.

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

• --no-login-paths

  Command-Line Format	--no-login-paths

  Skips reading options from the login path file.

  See --login-path for related information.

  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 Section 6.6.7, “mysql_config_editor — MySQL Configuration Utility”.

  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 8.4.1.2, “SHA-256 Pluggable Authentication”, and Section 8.4.1.1, “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 Command Options for Encrypted Connections.

• --ssl-fips-mode={OFF|ON|STRICT}

  Command-Line Format	--ssl-fips-mode={OFF|ON|STRICT}
  Deprecated	Yes
  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.

  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
  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”.

• --tls-sni-servername=server_name

  Command-Line Format	--tls-sni-servername=server_name
  Type	String

  When specified, the name is passed to the libmysqlclient C API library using the MYSQL_OPT_TLS_SNI_SERVERNAME option of mysql_options(). The server name is not case-sensitive. To show which server name the client specified for the current session, if any, check the Tls_sni_server_name status variable.

  Server Name Indication (SNI) is an extension to the TLS protocol (OpenSSL must be compiled using TLS extensions for this option to function). The MySQL implementation of SNI represents the client-side only.

• --tls-version=protocol_list

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

  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=#
  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”.