Provided by: mysql-client-core-5.7_5.7.33-0ubuntu0.16.04.1_amd64 
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 13.3.5, “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 13.7.2, “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:
shell> 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 2.11.12, “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:
shell> mysqlcheck [options] db_name [tbl_name ...]
shell> mysqlcheck [options] --databases db_name ...
shell> 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 4.2.2.2, “Using Option Files”.
• --help, -? Display a help message and exit.
• --all-databases, -A 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 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 Analyze the tables.
• --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 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 The directory where character sets are installed. See Section 10.15,
“Character Set Configuration”.
• --check, -c Check the tables for errors. This is the default operation.
• --check-only-changed, -C Check only tables that have changed since the last check or that have not
been closed properly.
• --check-upgrade, -g Invoke CHECK TABLE with the FOR UPGRADE option to check tables for
incompatibilities with the current version of the server. This option automatically enables the
--fix-db-names and --fix-table-names options.
• --compress Compress all information sent between the client and the server if possible. See
Section 4.2.6, “Connection Compression Control”.
• --databases, -B 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] 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 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 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 Use charset_name as the default character set. See
Section 10.15, “Character Set Configuration”.
• --defaults-extra-file=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. file_name is interpreted relative to the current directory if given as a relative path name
rather than a full path name.
For additional information about this and other option-file options, see Section 4.2.2.3, “Command-
Line Options that Affect Option-File Handling”.
• --defaults-file=file_name Use only the given option file. If the file does not exist or is otherwise
inaccessible, an error occurs. file_name is interpreted relative to the current directory if given
as a relative path name rather than a full path name.
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”.
• --defaults-group-suffix=str 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 the --defaults-group-suffix=_other option is given, 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, -e 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 A hint about which client-side authentication plugin to use. See
Section 6.2.13, “Pluggable Authentication”.
• --enable-cleartext-plugin Enable the mysql_clear_password cleartext authentication plugin. (See
Section 6.4.1.6, “Client-Side Cleartext Pluggable Authentication”.)
This option was added in MySQL 5.7.10.
• --fast, -F Check only tables that have not been closed properly.
• --fix-db-names Convert database names to 5.1 format. Only database names that contain special
characters are affected.
This option is deprecated in MySQL 5.7.6; expect it to be removed in a future version of MySQL. If it
is necessary to convert MySQL 5.0 database or table names, a workaround is to upgrade a MySQL 5.0
installation to MySQL 5.1 before upgrading to a more recent release.
• --fix-table-names Convert table names to 5.1 format. Only table names that contain special characters
are affected. This option also applies to views.
This option is deprecated in MySQL 5.7.6; expect it to be removed in a future version of MySQL. If it
is necessary to convert MySQL 5.0 database or table names, a workaround is to upgrade a MySQL 5.0
installation to MySQL 5.1 before upgrading to a more recent release.
• --force, -f Continue even if an SQL error occurs.
• --get-server-public-key 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 6.4.1.4, “Caching SHA-2 Pluggable
Authentication”.
The --get-server-public-key option was added in MySQL 5.7.23.
• --host=host_name, -h host_name Connect to the MySQL server on the given host.
• --login-path=name 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 4.2.2.3, “Command-
Line Options that Affect Option-File Handling”.
• --medium-check, -m 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 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, if it exists, is read in all cases. This permits
passwords to be specified in a safer way than on the command line even when --no-defaults is used.
(.mylogin.cnf is created by the mysql_config_editor utility. See mysql_config_editor(1).)
For additional information about this and other option-file options, see Section 4.2.2.3, “Command-
Line Options that Affect Option-File Handling”.
• --optimize, -o Optimize the tables.
• --password[=password], -p[password] 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 6.1.2.1, “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.
• --pipe, -W 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 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 6.2.13, “Pluggable Authentication”.
• --port=port_num, -P port_num For TCP/IP connections, the port number to use.
• --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 4.2.2.3, “Command-
Line Options that Affect Option-File Handling”.
• --protocol={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 4.2.5, “Connection Transport Protocols”.
• --quick, -q 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 Perform a repair that can fix almost anything except unique keys that are not unique.
• --secure-auth Do not send passwords to the server in old (pre-4.1) format. This prevents connections
except for servers that use the newer password format.
As of MySQL 5.7.5, this option is deprecated; expect it to be removed in a future MySQL release. It
is always enabled and attempting to disable it (--skip-secure-auth, --secure-auth=0) produces an
error. Before MySQL 5.7.5, this option is enabled by default but can be disabled.
Note
Passwords that use the pre-4.1 hashing method are less secure than passwords that use the native
password hashing method and should be avoided. Pre-4.1 passwords are deprecated and support for
them was removed in MySQL 5.7.5. For account upgrade instructions, see Section 6.4.1.3,
“Migrating Away from Pre-4.1 Password Hashing and the mysql_old_password Plugin”.
• --server-public-key-path=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 6.4.1.5,
“SHA-256 Pluggable Authentication”, and Section 6.4.1.4, “Caching SHA-2 Pluggable Authentication”.
The --server-public-key-path option was added in MySQL 5.7.23.
• --shared-memory-base-name=name 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 Silent mode. Print only error messages.
• --skip-database=db_name Do not include the named database (case-sensitive) in the operations
performed by mysqlcheck.
• --socket=path, -S path 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 SSL and indicate
where to find SSL keys and certificates. See the section called “Command Options for Encrypted
Connections”.
• --tables Override the --databases or -B option. All name arguments following the option are regarded
as table names.
• --tls-version=protocol_list 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 6.3.2, “Encrypted
Connection TLS Protocols and Ciphers”.
This option was added in MySQL 5.7.10.
• --use-frm For repair operations on MyISAM tables, get the table structure from the .frm file so that
the table can be repaired even if the .MYI header is corrupted.
• --user=user_name, -u user_name The user name of the MySQL account to use for connecting to the
server.
• --verbose, -v Verbose mode. Print information about the various stages of program operation.
• --version, -V Display version information and exit.
• --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.
COPYRIGHT
Copyright © 1997, 2020, 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/).