mysqlcheck man page on SmartOS
MYSQLCHECK(1) MySQL Database System MYSQLCHECK(1)
mysqlcheck - a table maintenance program
mysqlcheck [options] [db_name [tbl_name ...]]
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
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
note : The storage engine for the table doesn't support check
If mysqlcheck is unable to repair a table, see Section 2.10.4,
“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
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
│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. mysqlcheck also supports the options for processing
option files described at Section 22.214.171.124, “Command-Line Options that
Affect Option-File Handling”.
· --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
· --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, this option can
be used to select which interface is employed when 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-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
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 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.
Print some debugging information when the program exits.
Print debugging information and memory and CPU usage statistics
when the program exits.
Use charset_name as the default character set. See Section 10.5,
“Character Set Configuration”.
· --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!
The client-side authentication plugin to use. See Section 6.3.7,
This option was added in MySQL 5.6.2.
· --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
file. A “login path” is an option group that permits only a limited
set of options: host, user, and password. Think of a login path as
a set of values that indicate the server host and the credentials
for authenticating with the server. To create the login file, use
the mysql_config_editor utility. See mysql_config_editor(1). 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
· --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
Specifying a password on the command line should be considered
insecure. See Section 126.96.36.199, “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. It may be necessary to
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.
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
· --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 188.8.131.52, “Migrating Away from
Pre-4.1 Password Hashing and the mysql_old_password Plugin”.
· --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
· --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 184.108.40.206, “SSL Command Options”.
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
· --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.
Copyright © 1997, 2014, Oracle and/or its affiliates. All rights
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
For more information, please refer to the MySQL Reference Manual, which
may already be installed locally and which is also available online at
Oracle Corporation (http://dev.mysql.com/).
MySQL 5.6 03/14/2014 MYSQLCHECK(1)
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