mysqlanalyze
a table maintenance program
Synopsis
mysqlcheck
[options] [db_name
[tbl_name ...]]
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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 2.12.4, “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.
mysqlcheck supports the
following options, which can be specified on the command
line or in the [mysqlcheck] and [client] groups of an option
file. mysqlcheck also supports the options for
processing option files described at Section 4.2.3.4,
“Command-Line Options that Affect Option-File
Handling”.
•
--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.
•
--bind-address=ip_address
On a computer
having multiple network interfaces, this option can be used
to select which interface is employed when connecting to the
MySQL server.
This option is
supported only in the version of mysqlcheck that is
supplied with MySQL Cluster. It is not available in standard
MySQL Server 5.5 releases.
•
--character-sets-dir=path
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 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'.
•
--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”.
•
--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
The
client-side authentication plugin to use. See
Section 6.3.6, “Pluggable
Authentication”.
This option was
added in MySQL 5.5.10.
•
--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.
•
--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.
•
--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 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=path
The directory
in which to look for plugins. It may be necessary to specify
this option if the --default-auth
option is used to specify an authentication plugin but
mysqlcheck does not find it. See Section 6.3.6,
“Pluggable Authentication”.
This option was
added in MySQL 5.5.10.
•
--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 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.
•
--silent, -s
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.
•
--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 6.3.8.4,
“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.
copyright
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mysqlcheck
[tbl_name ...]]
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/).