mysqlcheck man page on DragonFly

mysqlcheck man page on DragonFly

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MYSQLCHECK(1) MySQL Database System MYSQLCHECK(1)

NAME
mysqlcheck - a table maintenance program

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, 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
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 2.11.4,
“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:

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
default behavior.

┌──────────────┬───────────────────────┐
│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. For information about option files used by MySQL programs,
see Section 4.2.6, “Using Option Files”.

· --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, except that the INFORMATION_SCHEMA and performace_schema
databases are not dumped. They can be dumped by explicitly naming
them with the --databases option.

· --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.

· --bind-address=ip_address

On a computer having multiple network interfaces, use this option
to select which interface to use for connecting to the MySQL
server.

· --character-sets-dir=dir_name

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
--fix-table-names options.

· --compress

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 any following names as table names. With this option, it
treats all name arguments as database names.

This option may be used to dump the INFORMATION_SCHEMA and
performace_schema databases, which normally are not dumped even
with the --all-databases option. (Also use the --skip-lock-tables
option.)

· --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.

· --debug-check

Print some debugging information when the program exits.

· --debug-info

Print debugging information and memory and CPU usage statistics
when the program exits.

· --default-character-set=charset_name

Use charset_name as the default character set. See Section 10.5,
“Character Set Configuration”.

· --defaults-extra-file=file_name

Read this option file after the global option file but (on Unix)
before the user option file. If the file does not exist or is
otherwise inaccessible, an error occurs. file_name is interpreted
relative to the current directory if given as a relative path name
rather than a full path name.

· --defaults-file=file_name

Use only the given option file. If the file does not exist or is
otherwise inaccessible, an error occurs. file_name is interpreted
relative to the current directory if given as a relative path name
rather than a full path name.

· --defaults-group-suffix=str

Read not only the usual option groups, but also groups with the
usual names and a suffix of str. For example, mysqlcheck normally
reads the [client] and [mysqlcheck] groups. If the
--defaults-group-suffix=_other option is given, mysqlcheck also
reads the [client_other] and [mysqlcheck_other] groups.

· --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!

· --default-auth=plugin

A hint about the client-side authentication plugin to use. See
Section 6.3.8, “Pluggable Authentication”.

· --enable-cleartext-plugin

Enable the mysql_clear_password cleartext authentication plugin.
(See Section 6.3.9.8, “The Cleartext Client-Side Authentication
Plugin”.)

This option was added in MySQL 5.7.10.

· --fast, -F

Check only tables that have not been closed properly.

· --fix-db-names

Convert database names to 5.1 format. Only database names that
contain special characters are affected.

This option is deprecated in MySQL 5.7.6 and will be removed in a
future version of MySQL. If it is necessary to convert MySQL 5.0
database or table names, a workaround is to upgrade a MySQL 5.0
installation to MySQL 5.1 before upgrading to a more recent
release.

· --fix-table-names

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.

· --login-path=name

Read options from the named login path in the .mylogin.cnf login
path file. A “login path” is an option group containing options
that specify which MySQL server to connect to and which account to
authenticate as. To create or modify a login path file, use the
mysql_config_editor utility. See mysql_config_editor(1).

· --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.

· --no-defaults

Do not read any option files. If program startup fails due to
reading unknown options from an option file, --no-defaults can be
used to prevent them from being read.

The exception is that the .mylogin.cnf file, if it exists, is read
in all cases. This permits passwords to be specified in a safer way
than on the command line even when --no-defaults is used.
(.mylogin.cnf is created by the mysql_config_editor utility. See
mysql_config_editor(1).)

· --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. See Section 6.1.2.1, “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.

· --plugin-dir=dir_name

The directory in which to look for plugins. Specify this option if
the --default-auth option is used to specify an authentication
plugin but mysqlcheck does not find it. See Section 6.3.8,
“Pluggable Authentication”.

· --port=port_num, -P port_num

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

· --print-defaults

Print the program name and all options that it gets from option
files.

· --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
permissible values, see Section 4.2.2, “Connecting to the MySQL
Server”.

· --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.

· --secure-auth

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 was added in MySQL 5.7.4.

As of MySQL 5.7.5, this option is deprecated and will be removed in
a future MySQL release. It is always enabled and attempting to
disable it (--skip-secure-auth, --secure-auth=0) produces an error.
Before MySQL 5.7.5, this option is enabled by default but can be
disabled.

Note
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 is removed in MySQL 5.7.5. For account upgrade
instructions, see Section 6.3.9.3, “Migrating Away from Pre-4.1
Password Hashing and the mysql_old_password Plugin”.

· --shared-memory-base-name=name

On Windows, the shared-memory name to use, for connections made
using shared memory to a local server. The default value is MYSQL.
The shared-memory name is case sensitive.

The server must be started with the --shared-memory option to
enable shared-memory connections.

· --silent, -s

Silent mode. Print only error messages.

· --skip-database=db_name

Do not include the named database (case sensitive) in the
operations performed by mysqlcheck.

· --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.

· --ssl*

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 6.3.12.4, “SSL Command Options”.

· --tables

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

· --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.

· --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
operation.

· --version, -V

Display version information and exit.

· --write-binlog

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.

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
Oracle Corporation (http://dev.mysql.com/).

MySQL 5.7 11/28/2015 MYSQLCHECK(1)

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