The mysqlcheck Table Maintenance and Repair Program

The mysqlcheck Table Maintenance and Repair Program
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The mysqlcheck client checks and repairs MyISAM tables. It can also optimize and analyze tables. mysqlcheck is available as of MySQL 3.23.38.

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, then sends the statements to the server to be executed.

There are three general ways to invoke mysqlcheck:

shell> mysqlcheck [options] db_name [tables]
shell> mysqlcheck [options] --databases DB1 [DB2 DB3...]
shell> mysqlcheck [options] --all-databases

If you don't name any tables or use the --databases or --all-databases option, entire databases will be checked.

mysqlcheck has a special feature compared to the other clients. 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 will repair tables by command.

The following names can be used to change mysqlcheck default behavior:

mysqlrepair	The default option will be `--repair`
mysqlanalyze	The default option will be `--analyze`
mysqloptimize	The default option will be `--optimize`

mysqlcheck supports the following options:

--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.

--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.

--auto-repair

If a checked table is corrupted, automatically fix it. Any necessary repairs are done after all tables have been checked.

--character-sets-dir=path

The directory where character sets are installed. See the section called “The Character Set Used for Data and Sorting”.

--check, -c

Check the tables for errors.

--check-only-changed, -C

Check only tables that have changed since the last check or that haven't been closed properly.

--compress

Compress all information sent between the client and the server if both support compression.

--databases, -B

Process all tables in the named databases. With this option, all name arguments are regarded as database names, not as table names.

--debug[=debug_options], -# [debug_options]

Write a debugging log. The debug_options string often is 'd:t:o,file_name'.

--default-character-set=charset

Use charset as the default character set. See the section called “The Character Set Used for Data and Sorting”.

--extended, -e

If you are using this option to check tables, it ensures that they are 100% consistent but will take 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!

--fast, -F

Check only tables that haven't been closed properly.

--force, -f

Continue even if an SQL error occurs.

--host=host_name, -h host_name

Connect to the MySQL 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 most cases.

--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 no password is given on the command line, you will be prompted for one.

--port=port_num, -P port_num

The TCP/IP port number to use for the connection.

--protocol={TCP | SOCKET | PIPE | MEMORY}

The connection protocol to use. New in MySQL 4.1.

--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

Do a repair that can fix almost anything except unique keys that aren't unique.

--silent, -s

Silent mode. Print only error messages.

--socket=path, -S path

The socket file to use for the connection.

--tables

Overrides the --databases or -B option. All arguments following the option are regarded as table names.

--user=user_name, -u user_name

The MySQL username 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.

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