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. 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.
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 the MariaDB Knowledge
Base 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.
The use of mysqlcheck with partitioned tables is not supported.
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 following names can be used to change mysqlcheck default
│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] option file
· --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.
The directory where character sets are installed.
· --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.
Default authentication client-side plugin to use.
Use charset_name as the default character set.
Set filename as the file to read default options from after the
global defaults files has been read. Must be given as first
Set filename as the file to read default options from, override
global defaults files. Must be given as first option.
· --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 will force
using the old, slow, repair with keycache method, instead of the
much faster repair by sorting.
· --fast, -F
Check only tables that have not been closed properly.
Convert database names to the format used since MySQL 5.1. Only
database names that contain special characters are affected.
Convert table names (including views) to the format used since
MySQL 5.1. Only table names that contain special characters are
Flush each table after check. This is useful if you don't want to
have the checked tables take up space in the caches after the
· --force, -f
Continue even if an SQL error occurs.
· --host=host_name, -h host_name
Connect to the MariaDB server on the given host.
· --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
Do not read default options from any option file. This must be
given as the first argument.
· --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. You can use an option file to avoid giving the password
on the command line.
· --persistent, -Z
Used with ANALYZE TABLE to append the option PERSISENT FOR ALL.
· --pipe, -W
On Windows, connect to the server via a named pipe. This option
applies only if the server supports named-pipe connections.
Directory for client-side plugins.
· --port=port_num, -P port_num
The TCP/IP port number to use for the connection.
Print the program argument list and exit. This must be given as
the first argument.
Perform the requested operation on tables. Defaults to on; use
--skip-process-tables to disable.
Perform the requested operation (only CHECK VIEW or REPAIR VIEW).
Possible values are NO, YES (correct the checksum, if necessary,
add the mariadb-version field), UPGRADE_FROM_MYSQL (same as YES
and toggle the algorithm MERGE<->TEMPTABLE.
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.
· --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.
· --silent, -s
Silent mode. Print only error messages.
Don't process the database (case-sensitive) specified as
· --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.
Enable SSL for connection (automatically enabled with other
flags). Disable with --skip-ssl.
CA file in PEM format (check OpenSSL docs, implies --ssl).
CA directory (check OpenSSL docs, implies --ssl).
X509 cert in PEM format (check OpenSSL docs, implies --ssl).
SSL cipher to use (check OpenSSL docs, implies --ssl).
X509 key in PEM format (check OpenSSL docs, implies --ssl).
Certificate revocation list (check OpenSSL docs, implies --ssl).
Certificate revocation list path (check OpenSSL docs, implies
Verify server's "Common Name" in its cert against hostname used
when connecting. This option is disabled by default.
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 MariaDB user name to use when connecting to the server.
· --verbose, -v
Verbose mode. Print information about the various stages of
program operation. Using one --verbose option will give you more
information about what mysqlcheck is doing.
Using two --verbose options will also give you connection
Using it 3 times will print out all CHECK, RENAME and ALTER TABLE
during the check phase.
· --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 2007-2008 MySQL AB, 2008-2010 Sun Microsystems, Inc.,
2010-2015 MariaDB Foundation
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MariaDB 10.1 14/12/2015 MYSQLCHECK(1)