4.5.3 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 13.3.6, “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 13.7.3, “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 ttest.tnote : The storage engine for the table doesn't support checkIf mysqlcheck is unable to repair a table, see Section 2.11.13, “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.
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-databasesIf 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 4.2.2.2, “Using Option Files”.
Table 4.13 mysqlcheck Options
| Option Name | Description | Introduced | Deprecated |
|---|---|---|---|
| --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 | 8.0.18 | |
| --compression-algorithms | Permitted compression algorithms for connections to server | 8.0.18 | |
| --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-auth | Authentication plugin to use | ||
| --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 | ||
| --optimize | Optimize the tables | ||
| --password | Password to use when connecting to server | ||
| --password1 | First multifactor authentication password to use when connecting to server | 8.0.27 | |
| --password2 | Second multifactor authentication password to use when connecting to server | 8.0.27 | |
| --password3 | Third multifactor authentication password to use when connecting to server | 8.0.27 | |
| --pipe | Connect to server using named pipe (Windows only) | ||
| --plugin-dir | Directory where plugins are installed | ||
| --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-crl | File that contains certificate revocation lists | ||
| --ssl-crlpath | Directory that contains certificate revocation-list files | ||
| --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 | 8.0.29 | |
| --ssl-session-data-continue-on-failed-reuse | Whether to establish connections if session reuse fails | 8.0.29 | |
| --tables | Overrides the --databases or -B option | ||
| --tls-ciphersuites | Permissible TLSv1.3 ciphersuites for encrypted connections | 8.0.16 | |
| --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 | 8.0.18 |
--help,-?Display a help message and exit.
--all-databases,-ACheck all tables in all databases. This is the same as using the
--databasesoption and naming all the databases on the command line, except that theINFORMATION_SCHEMAandperformance_schemadatabases are not checked. They can be checked by explicitly naming them with the--databasesoption.--all-in-1,-1Instead 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,-aAnalyze the tables.
If a checked table is corrupted, automatically fix it. Any necessary repairs are done after all tables have been checked.
On a computer having multiple network interfaces, use this option to select which interface to use for connecting to the MySQL server.
The directory where character sets are installed. See Section 10.15, “Character Set Configuration”.
--check,-cCheck the tables for errors. This is the default operation.
Check only tables that have changed since the last check or that have not been closed properly.
--check-upgrade,-gInvoke
CHECK TABLEwith theFOR UPGRADEoption to check tables for incompatibilities with the current version of the server.Compress all information sent between the client and the server if possible. See Section 4.2.8, “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 Configuring Legacy Connection Compression.
--compression-algorithms=valueThe permitted compression algorithms for connections to the server. The available algorithms are the same as for the
protocol_compression_algorithmssystem variable. The default value isuncompressed.For more information, see Section 4.2.8, “Connection Compression Control”.
This option was added in MySQL 8.0.18.
--databases,-BProcess 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]Write a debugging log. A typical
debug_optionsstring isd:t:o,. The default isfile_named: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.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.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_nameUse
charset_nameas the default character set. See Section 10.15, “Character Set Configuration”.--defaults-extra-file=file_nameRead 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_nameis 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 4.2.2.3, “Command-Line Options that Affect Option-File Handling”.
Use only the given option file. If the file does not exist or is otherwise inaccessible, an error occurs. If
file_nameis 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 4.2.2.3, “Command-Line Options that Affect Option-File Handling”.
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 4.2.2.3, “Command-Line Options that Affect Option-File Handling”.
--extended,-eIf 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!
A hint about which client-side authentication plugin to use. See Section 6.2.17, “Pluggable Authentication”.
Enable the
mysql_clear_passwordcleartext authentication plugin. (See Section 6.4.1.4, “Client-Side Cleartext Pluggable Authentication”.)--fast,-FCheck only tables that have not been closed properly.
--force,-fContinue even if an SQL error occurs.
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_passwordauthentication 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=is given and specifies a valid public key file, it takes precedence overfile_name--get-server-public-key.For information about the
caching_sha2_passwordplugin, see Section 6.4.1.2, “Caching SHA-2 Pluggable Authentication”.
