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 Syntax”, 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 mysql_upgrade because that
program invokes mysqlcheck to check all
tables and repair them if necessary.)
mysqlcheck is similar in function to myisamchk, but works differently. The main operational difference is that mysqlcheck must be used when the mysqld server is running, whereas myisamchk should be used when it is not. The benefit of using mysqlcheck is 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”.
The MyISAM storage engine supports all four
maintenance operations, so mysqlcheck can be
used to perform any of them on MyISAM tables.
Other storage engines do not necessarily support all operations.
In such cases, an error message is displayed. For example, if
test.t is a 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 2.11.4, “Rebuilding or Repairing Tables or Indexes” for manual table repair
strategies. This will be 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:
shell>mysqlcheck [shell>options]db_name[tbl_name...]mysqlcheck [shell>options] --databasesdb_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 4.2.6, “Using Option Files”.
Table 4.10 mysqlcheck Options
| Format | Description | Introduced |
|---|---|---|
| --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 | 5.6.1 |
| --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 | |
| --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 | 5.6.2 |
| --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 | 5.6.28 |
| --extended | Check and repair tables | |
| --fast | Check only tables that have not been closed properly | |
| --fix-db-names | Convert database names to 5.1 format | |
| --fix-table-names | Convert table names to 5.1 format | |
| --force | Continue even if an SQL error occurs | |
| --help | Display help message and exit | |
| --host | Connect to MySQL server on given host | |
| --login-path | Read login path options from .mylogin.cnf | 5.6.6 |
| --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 | |
| --pipe | On Windows, connect to server using named pipe | |
| --plugin-dir | Directory where plugins are installed | 5.6.2 |
| --port | TCP/IP port number to use for connection | |
| --print-defaults | Print default options | |
| --protocol | Connection 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 | |
| --secure-auth | Do not send passwords to server in old (pre-4.1) format | 5.6.17 |
| --shared-memory-base-name | The name of shared memory to use for shared-memory connections | |
| --silent | Silent mode | |
| --skip-database | Omit this database from performed operations | 5.6.11 |
| --socket | For connections to localhost, the Unix socket file to use | |
| --ssl | Enable secure connection | |
| --ssl-ca | Path of file that contains list of trusted SSL CAs | |
| --ssl-capath | Path of directory that contains trusted SSL CA certificates in PEM format | |
| --ssl-cert | Path of file that contains X509 certificate in PEM format | |
| --ssl-cipher | List of permitted ciphers to use for connection encryption | |
| --ssl-crl | Path of file that contains certificate revocation lists | 5.6.3 |
| --ssl-crlpath | Path of directory that contains certificate revocation list files | 5.6.3 |
| --ssl-key | Path of file that contains X509 key in PEM format | |
| --ssl-mode | Security state of connection to server | 5.6.30 |
| --ssl-verify-server-cert | Verify server certificate Common Name value against host name used when connecting to server | |
| --tables | Overrides the --databases or -B option | |
| --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. |
--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
performace_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.
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.
This option is supported beginning with MySQL 5.6.1.
The directory where character sets are installed. See Section 10.5, “Character Set Configuration”.
--check,
-c
Check 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,
-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 all information sent between the client and the server if both support compression.
--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,.
The default is file_named:t:o.
Print some debugging information when the program exits.
Print debugging information and memory and CPU usage statistics when the program exits.
--default-character-set=
charset_name
Use charset_name as the default
character set. See Section 10.5, “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.
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.
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.
--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!
A hint about the client-side authentication plugin to use. See Section 6.3.7, “Pluggable Authentication”.
This option was added in MySQL 5.6.2.
Enable the mysql_clear_password cleartext
authentication plugin. (See
Section 6.5.1.7, “The Cleartext Client-Side Authentication Plugin”.)
This option was added in MySQL 5.6.28.
--fast,
-F
Check only tables that have not been closed properly.
Convert database names to 5.1 format. Only database names that contain special characters are affected.
Convert table names to 5.1 format. Only table names that contain special characters are affected. This option also applies to views.
--force,
-f
Continue even if an SQL error occurs.
--host=,
host_name-h
host_name
Connect to the MySQL server on the given host.
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 4.6.6, “mysql_config_editor — MySQL Configuration Utility”. This option was added
in MySQL 5.6.6.
--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.
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
Section 4.6.6, “mysql_config_editor — MySQL Configuration Utility”.)
--optimize,
-o
Optimize the tables.
--password[=,
password]-p[
password]
The password to use when connecting to the server. If you
use the short option form (-p), you
cannot have a space between the option
and the password. If you omit the
password value following the
--password or
-p option on the command line,
mysqlcheck prompts for one.
Specifying a password on the command line should be considered insecure. See Section 6.1.2.1, “End-User Guidelines for Password Security”. You can use an option file to avoid giving the password on the command line.
--pipe,
-W
On Windows, connect to the server using a named pipe. This option applies only if the server supports named-pipe connections.
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 6.3.7, “Pluggable Authentication”.
This option was added in MySQL 5.6.2.
--port=,
port_num-P
port_num
The TCP/IP port number to use for the connection.
Print the program name and all options that it gets from option files.
--protocol={TCP|SOCKET|PIPE|MEMORY}
The connection protocol to use for connecting to the server. It is useful when the other connection parameters normally would cause a protocol to be used other than the one you want. For details on the permissible values, see Section 4.2.2, “Connecting to the MySQL Server”.
--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.
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. This option is enabled by default;
use
--skip-secure-auth
to disable it. This option was added in MySQL 5.6.17.
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 will be removed in a future MySQL release. For account upgrade instructions, see Section 6.5.1.3, “Migrating Away from Pre-4.1 Password Hashing and the mysql_old_password Plugin”.
This option is deprecated and will be removed in a future release. As of MySQL 5.7.5, it is always enabled and attempting to disable it produces an error.
--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.
The server must be started with the
--shared-memory option to
enable shared-memory connections.
--silent,
-s
Silent mode. Print only error messages.
Do not include the named database (case sensitive) in the operations performed by mysqlcheck. This option was added in MySQL 5.6.11.
--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.
Options that begin with --ssl specify
whether to connect to the server using SSL and indicate
where to find SSL keys and certificates. See
Section 6.4.5, “Command Options for Secure Connections”.
Override the --databases
or -B option. All name arguments following
the option are regarded as table names.
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 MySQL user name to use when connecting to the server.
--verbose,
-v
Verbose mode. Print information about the various stages of program operation.
--version,
-V
Display version information and exit.
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 replication
slaves or run when using the binary logs for recovery from
backup.