6.5.3 mysqlcheck — A Table Maintenance Program (original) (raw)

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 (seeSection 15.3.6, “LOCK TABLES and UNLOCK TABLES Statements”, for more information aboutREAD 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 ofmysqlcheck 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 themysqld server is running, which means that you do not have to stop the server to perform table maintenance.

mysqlcheck uses the SQL statementsCHECK TABLE,REPAIR TABLE,ANALYZE TABLE, andOPTIMIZE 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 inSection 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 anMEMORY 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, forInnoDB tables, which can be checked withCHECK 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 invokemysqlcheck:

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

If you do not name any tables following_dbname_ 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 ofmysqlcheck namedmysqlrepair, or make a symbolic link tomysqlcheck namedmysqlrepair. If you invokemysqlrepair, it repairs tables.

The names shown in the following table can be used to changemysqlcheck default behavior.

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 andperformance_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. SeeSection 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 theFOR 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. SeeSection 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. SeeConfiguring Legacy Connection Compression.

• --compression-algorithms=value

  Command-Line Format	--compression-algorithms=value
  Introduced	8.0.18
  Type	Set
  Default Value	uncompressed
  Valid Values	zlibzstduncompressed
  The permitted compression algorithms for connections to the server. The available algorithms are the same as for theprotocol_compression_algorithms system variable. The default value isuncompressed.
  For more information, seeSection 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],-# [_`debugoptions`_]

  Command-Line Format	--debug[=debug_options]
  Type	String
  Default Value	d:t:o
  Write a debugging log. A typical_debugoptions_ string isd:t:o,_`filename`_. The default is d:t:o.
  This option is available only if MySQL was built usingWITH_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 usingWITH_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 usingWITH_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 charsetname 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_filename_ 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_filename_ 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. (SeeSection 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 thecaching_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 thecaching_sha2_password plugin, seeSection 8.4.1.2, “Caching SHA-2 Pluggable Authentication”.

• --host=host_name,-h _`hostname`_

  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 themysql_config_editor utility. SeeSection 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”.

• --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 themysql_config_editor utility. SeeSection 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. SeeSection 8.1.2.1, “End-User Guidelines for Password Security”.
  To explicitly specify that there is no password and thatmysqlcheck 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. SeeSection 8.1.2.1, “End-User Guidelines for Password Security”.
  To explicitly specify that there is no password and thatmysqlcheck 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 thenamed_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 thenamed_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 butmysqlcheck does not find it. SeeSection 8.2.17, “Pluggable Authentication”.

• --port=port_num,-P _`portnum`_

  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	TCPSOCKETPIPEMEMORY
  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, seeSection 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 thesha256_password orcaching_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, seeSection 8.4.1.3, “SHA-256 Pluggable Authentication”, andSection 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 theshared_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 thenamed_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. SeeCommand 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 | OFFONSTRICT |
  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 isOFF. In this case, setting--ssl-fips-mode toON 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, seeSection 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, seeSection 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 _`username`_

  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 thatANALYZE TABLE,OPTIMIZE TABLE, andREPAIR 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 defaultzstd compression level is 3. The compression level setting has no effect on connections that do not use zstd compression.
  For more information, seeSection 6.2.8, “Connection Compression Control”.
  This option was added in MySQL 8.0.18.