MYSQLCHECK(1) MySQL Database System MYSQLCHECK(1)
mysqlcheck - a table maintenance and repair program
mysqlcheck [options] [db_name [tbl_name ...]]
The mysqlcheck client checks, repairs, optimizes, and analyzes tables.
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 check or repair your tables.
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 Chapter 13, SQL Statement
The MyISAM storage engine supports all four statements, so mysqlcheck
can be used to perform all four operations 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 doesnt support check
There are three general ways to invoke mysqlcheck:
shell> mysqlcheck [options] db_name [tables]
shell> mysqlcheck [options] --databases db_name1 [db_name2 db_name3...]
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 behavior:
|mysqlrepair | The default option is |
| | --repair |
|mysqlanalyze | The default option is |
| | --analyze |
|mysqloptimize | The default option is |
| | --optimize |
mysqlcheck supports the following options:
Display a help message and exit.
Check all tables in all databases. This is the same as using the
--databases option and naming all the databases on the command line.
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 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. See Section 9.1,
The Character Set Used for Data and Sorting.
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.
Invoke CHECK TABLE with the FOR UPGRADE option to check tables for
incompatibilities with the current version of the server. This
option was added in MySQL 5.0.19.
Compress all information sent between the client and the server if
both support compression.
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 often
Use charset_name as the default character set. See Section 9.1, The
Character Set Used for Data and Sorting.
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!
Check only tables that have not been closed properly.
Continue even if an SQL error occurs.
--host=host_name, -h host_name
Connect to the MySQL server on the given host.
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 the tables.
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, you are prompted for
Specifying a password on the command line should be considered
insecure. See Section 7.6, Keeping Your Password Secure.
--port=port_num, -P port_num
The TCP/IP port number to use for the connection.
The connection protocol to use.
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.
Perform a repair that can fix almost anything except unique keys
that are not unique.
Silent mode. Print only error messages.
--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 via SSL and indicate where to find SSL keys and certificates.
See Section 7.7.3, SSL Command Options.
Overrides 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 username to use when connecting to the server.
Verbose mode. Print information about the various stages of program
Display version information and exit.
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MySQL 5.0 12/20/2006 MYSQLCHECK(1)