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. 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 12.5.2, "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 2.18.4,
"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.
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:
mysqlrepair, it repairs tables.
The following names can be used to change mysqlcheck default behavior.
+--------------+-----------------------+
|mysqlrepair | The default option is |
| | --repair |
+--------------+-----------------------+
|mysqlanalyze | The default option is |
| | --analyze |
+--------------+-----------------------+
|mysqloptimize | The default option is |
| | --optimize |
+--------------+-----------------------+
mysqlcheck supports the options in the following list. It also reads
option files and supports the options for processing them described at
Section 4.2.3.2.1, "Command-Line Options that Affect Option-File
Handling".
o --help, -?
Display a help message and exit.
o --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.
o --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.
o --analyze, -a
Analyze the tables.
o --auto-repair
If a checked table is corrupted, automatically fix it. Any necessary
repairs are done after all tables have been checked.
o --character-sets-dir=path
The directory where character sets are installed. See Section 9.2,
"The Character Set Used for Data and Sorting".
o --check, -c
Check the tables for errors. This is the default operation.
o --check-only-changed, -C
Compress all information sent between the client and the server if
both support compression.
o --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.
o --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'.
o --default-character-set=charset_name
Use charset_name as the default character set. See Section 9.2, "The
Character Set Used for Data and Sorting".
o --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!
o --fast, -F
Check only tables that have not been closed properly.
o --force, -f
Continue even if an SQL error occurs.
o --host=host_name, -h host_name
Connect to the MySQL server on the given host.
o --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.
o --optimize, -o
Optimize the tables.
o --password[=password], -p[password]
The password to use when connecting to the server. If you use the
applies only for connections to a local server, and only if the
server supports named-pipe connections.
o --port=port_num, -P port_num
The TCP/IP port number to use for the connection.
o --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
allowable values, see Section 4.2.2, "Connecting to the MySQL
Server".
o --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.
o --repair, -r
Perform a repair that can fix almost anything except unique keys
that are not unique.
o --silent, -s
Silent mode. Print only error messages.
o --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.
o --ssl*
Options that begin with --ssl specify whether to connect to the
server via SSL and indicate where to find SSL keys and certificates.
See Section 5.5.7.3, "SSL Command Options".
o --tables
Overrides the --databases or -B option. All name arguments following
the option are regarded as table names.
o --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.
Display version information and exit.
COPYRIGHT
Copyright 2007-2008 MySQL AB, 2009 Sun Microsystems, Inc.
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
Sun Microsystems, Inc. (http://www.mysql.com/).
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