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 13.3.6, “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 t
test.t
note : The storage engine for the table doesn't support check
If mysqlcheck is unable to repair a table, see
Section 2.11.13, “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.
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 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.
•
--compress 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 the section called
“Configuring Legacy Connection Compression”.
•
--compression-algorithms=value
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 4.2.8, “Connection
Compression Control”.
This option was added in MySQL 8.0.18.
•--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. 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 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. 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 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 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,
-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 6.2.17, “Pluggable Authentication”.
•--enable-cleartext-plugin Enable the
mysql_clear_password cleartext authentication plugin. (See
Section 6.4.1.4, “Client-Side Cleartext Pluggable
Authentication”.)
•--fast, -F Check only tables that
have not been closed properly.
•--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 6.4.1.2, “Caching SHA-2 Pluggable
Authentication”.
•--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 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 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.
•
--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 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-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 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 6.2.17,
“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 4.2.7, “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.
•
--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 6.4.1.3, “SHA-256
Pluggable Authentication”, and Section 6.4.1.2,
“Caching SHA-2 Pluggable Authentication”.
•
--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 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} 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 6.8, “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.
•--tables Override the --databases
or -B option. All name arguments following the option are regarded as
table names.
•
--tls-ciphersuites=ciphersuite_list
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 6.3.2, “Encrypted
Connection TLS Protocols and Ciphers”.
This option was added in MySQL 8.0.16.
•--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”.
•--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 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.
•
--zstd-compression-level=level
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 4.2.8, “Connection
Compression Control”.
This option was added in MySQL 8.0.18.