~ubuntu-branches/ubuntu/wily/mysql-5.6/wily

'\" t

.\"     Title: \fBmyisamchk\fR

.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]

.\" Generator: DocBook XSL Stylesheets v1.78.1 <http://docbook.sf.net/>

.\"      Date: 05/05/2015

.\"    Manual: MySQL Database System

.\"    Source: MySQL 5.6

.\"  Language: English

.\"

.TH "\FBMYISAMCHK\FR" "1" "05/05/2015" "MySQL 5\&.6" "MySQL Database System"

.\" -----------------------------------------------------------------

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.ie \n(.g .ds Aq \(aq

.el       .ds Aq '

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.nh

.\" disable justification (adjust text to left margin only)

.ad l

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.\" * MAIN CONTENT STARTS HERE *

.\" -----------------------------------------------------------------

.\" myisamchk

.SH "NAME"

myisamchk \- MyISAM table\-maintenance utility

.SH "SYNOPSIS"

.HP \w'\fBmyisamchk\ [\fR\fB\fIoptions\fR\fR\fB]\ \fR\fB\fItbl_name\fR\fR\fB\ \&.\&.\&.\fR\ 'u

\fBmyisamchk [\fR\fB\fIoptions\fR\fR\fB] \fR\fB\fItbl_name\fR\fR\fB \&.\&.\&.\fR

.SH "DESCRIPTION"

.PP

The

\fBmyisamchk\fR

utility gets information about your database tables or checks, repairs, or optimizes them\&.

\fBmyisamchk\fR

works with

MyISAM

tables (tables that have

\&.MYD

and

\&.MYI

files for storing data and indexes)\&.

.PP

You can also use the

CHECK TABLE

and

REPAIR TABLE

statements to check and repair

MyISAM

tables\&. See

Section\ \&13.7.2.2, \(lqCHECK TABLE Syntax\(rq, and

Section\ \&13.7.2.5, \(lqREPAIR TABLE Syntax\(rq\&.

.PP

The use of

\fBmyisamchk\fR

with partitioned tables is not supported\&.

.if n \{\

.sp

.\}

.RS 4

.it 1 an-trap

.nr an-no-space-flag 1

.nr an-break-flag 1

.br

.ps +1

\fBCaution\fR

.ps -1

.br

.PP

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\&.

.sp .5v

.RE

.PP

Invoke

\fBmyisamchk\fR

like this:

.sp

.if n \{\

.RS 4

.\}

.nf

shell> \fBmyisamchk [\fR\fB\fIoptions\fR\fR\fB] \fR\fB\fItbl_name\fR\fR\fB \&.\&.\&.\fR

.fi

.if n \{\

.RE

.\}

.PP

The

\fIoptions\fR

specify what you want

\fBmyisamchk\fR

to do\&. They are described in the following sections\&. You can also get a list of options by invoking

\fBmyisamchk \-\-help\fR\&.

.PP

With no options,

\fBmyisamchk\fR

simply checks your table as the default operation\&. To get more information or to tell

\fBmyisamchk\fR

to take corrective action, specify options as described in the following discussion\&.

.PP

\fItbl_name\fR

is the database table you want to check or repair\&. If you run

\fBmyisamchk\fR

somewhere other than in the database directory, you must specify the path to the database directory, because

\fBmyisamchk\fR

has no idea where the database is located\&. In fact,

\fBmyisamchk\fR

does not actually care whether the files you are working on are located in a database directory\&. You can copy the files that correspond to a database table into some other location and perform recovery operations on them there\&.

.PP

You can name several tables on the

\fBmyisamchk\fR

command line if you wish\&. You can also specify a table by naming its index file (the file with the

\&.MYI

suffix)\&. This enables you to specify all tables in a directory by using the pattern

*\&.MYI\&. For example, if you are in a database directory, you can check all the

MyISAM

tables in that directory like this:

.sp

.if n \{\

.RS 4

.\}

.nf

shell> \fBmyisamchk *\&.MYI\fR

.fi

.if n \{\

.RE

.\}

.PP

If you are not in the database directory, you can check all the tables there by specifying the path to the directory:

.sp

.if n \{\

.RS 4

.\}

.nf

shell> \fBmyisamchk \fR\fB\fI/path/to/database_dir/\fR\fR\fB*\&.MYI\fR

.fi

.if n \{\

.RE

.\}

.PP

You can even check all tables in all databases by specifying a wildcard with the path to the MySQL data directory:

.sp

.if n \{\

.RS 4

.\}

.nf

shell> \fBmyisamchk \fR\fB\fI/path/to/datadir/*/*\fR\fR\fB\&.MYI\fR

.fi

.if n \{\

.RE

.\}

.PP

The recommended way to quickly check all

MyISAM

tables is:

.sp

.if n \{\

.RS 4

.\}

.nf

shell> \fBmyisamchk \-\-silent \-\-fast \fR\fB\fI/path/to/datadir/*/*\fR\fR\fB\&.MYI\fR

.fi

.if n \{\

.RE

.\}

.PP

If you want to check all

MyISAM

tables and repair any that are corrupted, you can use the following command:

.sp

.if n \{\

.RS 4

.\}

.nf

shell> \fBmyisamchk \-\-silent \-\-force \-\-fast \-\-update\-state \e\fR

          \fB\-\-key_buffer_size=64M \-\-myisam_sort_buffer_size=64M \e\fR

          \fB\-\-read_buffer_size=1M \-\-write_buffer_size=1M \e\fR

          \fB\fI/path/to/datadir/*/*\fR\fR\fB\&.MYI\fR

.fi

.if n \{\

.RE

.\}

.PP

This command assumes that you have more than 64MB free\&. For more information about memory allocation with

\fBmyisamchk\fR, see

the section called \(lqMYISAMCHK MEMORY USAGE\(rq\&.

.PP

For additional information about using

\fBmyisamchk\fR, see

Section\ \&7.6, \(lqMyISAM Table Maintenance and Crash Recovery\(rq\&.

.if n \{\

.sp

.\}

.RS 4

.it 1 an-trap

.nr an-no-space-flag 1

.nr an-break-flag 1

.br

.ps +1

\fBImportant\fR

.ps -1

.br

.PP

\fIYou must ensure that no other program is using the tables while you are running \fR\fI\fBmyisamchk\fR\fR\&. The most effective means of doing so is to shut down the MySQL server while running

\fBmyisamchk\fR, or to lock all tables that

\fBmyisamchk\fR

is being used on\&.

.PP

Otherwise, when you run

\fBmyisamchk\fR, it may display the following error message:

.sp

.if n \{\

.RS 4

.\}

.nf

warning: clients are using or haven\*(Aqt closed the table properly

.fi

.if n \{\

.RE

.\}

.PP

This means that you are trying to check a table that has been updated by another program (such as the

\fBmysqld\fR

server) that hasn\*(Aqt yet closed the file or that has died without closing the file properly, which can sometimes lead to the corruption of one or more

MyISAM

tables\&.

.PP

If

\fBmysqld\fR

is running, you must force it to flush any table modifications that are still buffered in memory by using

FLUSH TABLES\&. You should then ensure that no one is using the tables while you are running

\fBmyisamchk\fR

.PP

However, the easiest way to avoid this problem is to use

CHECK TABLE

instead of

\fBmyisamchk\fR

to check tables\&. See

Section\ \&13.7.2.2, \(lqCHECK TABLE Syntax\(rq\&.

.sp .5v

.RE

.PP

\fBmyisamchk\fR

supports the following options, which can be specified on the command line or in the

[myisamchk]

group of an option file\&. For information about option files used by MySQL programs, see

Section\ \&4.2.6, \(lqUsing Option Files\(rq\&.

.SH "MYISAMCHK GENERAL OPTIONS"

.\" options: myisamchk

.\" myisamchk: options

.PP

The options described in this section can be used for any type of table maintenance operation performed by

\fBmyisamchk\fR\&. The sections following this one describe options that pertain only to specific operations, such as table checking or repairing\&.

.sp

.RS 4

.ie n \{\

\h'-04'\(bu\h'+03'\c

.\}

.el \{\

.sp -1

.IP \(bu 2.3

.\}

.\" myisamchk: help option

.\" help option: myisamchk

\fB\-\-help\fR,

\fB\-?\fR

.sp

Display a help message and exit\&. Options are grouped by type of operation\&.

.RE

.sp

.RS 4

.ie n \{\

\h'-04'\(bu\h'+03'\c

.\}

.el \{\

.sp -1

.IP \(bu 2.3

.\}

.\" myisamchk: HELP option

.\" HELP option: myisamchk

\fB\-\-HELP\fR,

\fB\-H\fR

.sp

Display a help message and exit\&. Options are presented in a single list\&.

.RE

.sp

.RS 4

.ie n \{\

\h'-04'\(bu\h'+03'\c

.\}

.el \{\

.sp -1

.IP \(bu 2.3

.\}

.\" myisamchk: debug option

.\" debug option: myisamchk

\fB\-\-debug=\fR\fB\fIdebug_options\fR\fR,

\fB\-# \fR\fB\fIdebug_options\fR\fR

.sp

Write a debugging log\&. A typical

\fIdebug_options\fR

string is

d:t:o,\fIfile_name\fR\&. The default is

d:t:o,/tmp/myisamchk\&.trace\&.

.RE

.sp

.RS 4

.ie n \{\

\h'-04'\(bu\h'+03'\c

.\}

.el \{\

.sp -1

.IP \(bu 2.3

.\}

.\" myisamchk: defaults-extra-file option

.\" defaults-extra-file option: myisamchk

\fB\-\-defaults\-extra\-file=\fR\fB\fIfile_name\fR\fR

.sp

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\&.

\fIfile_name\fR

is interpreted relative to the current directory if given as a relative path name rather than a full path name\&.

.RE

.sp

.RS 4

.ie n \{\

\h'-04'\(bu\h'+03'\c

.\}

.el \{\

.sp -1

.IP \(bu 2.3

.\}

.\" myisamchk: defaults-file option

.\" defaults-file option: myisamchk

\fB\-\-defaults\-file=\fR\fB\fIfile_name\fR\fR

.sp

Use only the given option file\&. If the file does not exist or is otherwise inaccessible, an error occurs\&.

\fIfile_name\fR

is interpreted relative to the current directory if given as a relative path name rather than a full path name\&.

.RE

.sp

.RS 4

.ie n \{\

\h'-04'\(bu\h'+03'\c

.\}

.el \{\

.sp -1

.IP \(bu 2.3

.\}

.\" myisamchk: defaults-group-suffix option

.\" defaults-group-suffix option: myisamchk

\fB\-\-defaults\-group\-suffix=\fR\fB\fIstr\fR\fR

.sp

Read not only the usual option groups, but also groups with the usual names and a suffix of

\fIstr\fR\&. For example,

\fBmyisamchk\fR

normally reads the

[myisamchk]

group\&. If the

\fB\-\-defaults\-group\-suffix=_other\fR

option is given,

\fBmyisamchk\fR

also reads the

[myisamchk_other]

group\&.

.RE

.sp

.RS 4

.ie n \{\

\h'-04'\(bu\h'+03'\c

.\}

.el \{\

.sp -1

.IP \(bu 2.3

.\}

.\" myisamchk: no-defaults option

.\" no-defaults option: myisamchk

\fB\-\-no\-defaults\fR

.sp

Do not read any option files\&. If program startup fails due to reading unknown options from an option file,

\fB\-\-no\-defaults\fR

can be used to prevent them from being read\&.

.sp

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

\fB\-\-no\-defaults\fR

is used\&. (\&.mylogin\&.cnf

is created by the

\fBmysql_config_editor\fR

utility\&. See

\fBmysql_config_editor\fR(1)\&.)

.RE

.sp

.RS 4

.ie n \{\

\h'-04'\(bu\h'+03'\c

.\}

.el \{\

.sp -1

.IP \(bu 2.3

.\}

.\" myisamchk: print-defaults option

.\" print-defaults option: myisamchk

\fB\-\-print\-defaults\fR

.sp

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

.RE

.sp

.RS 4

.ie n \{\

\h'-04'\(bu\h'+03'\c

.\}

.el \{\

.sp -1

.IP \(bu 2.3

.\}

.\" myisamchk: silent option

.\" silent option: myisamchk

\fB\-\-silent\fR,

\fB\-s\fR

.sp

Silent mode\&. Write output only when errors occur\&. You can use

\fB\-s\fR

twice (\fB\-ss\fR) to make

\fBmyisamchk\fR

very silent\&.

.RE

.sp

.RS 4

.ie n \{\

\h'-04'\(bu\h'+03'\c

.\}

.el \{\

.sp -1

.IP \(bu 2.3

.\}

.\" myisamchk: verbose option

.\" verbose option: myisamchk

\fB\-\-verbose\fR,

\fB\-v\fR

.sp

Verbose mode\&. Print more information about what the program does\&. This can be used with

\fB\-d\fR

and

\fB\-e\fR\&. Use

\fB\-v\fR

multiple times (\fB\-vv\fR,

\fB\-vvv\fR) for even more output\&.

.RE

.sp

.RS 4

.ie n \{\

\h'-04'\(bu\h'+03'\c

.\}

.el \{\

.sp -1

.IP \(bu 2.3

.\}

.\" myisamchk: version option

.\" version option: myisamchk

\fB\-\-version\fR,

\fB\-V\fR

.sp

Display version information and exit\&.

.RE

.sp

.RS 4

.ie n \{\

\h'-04'\(bu\h'+03'\c

.\}

.el \{\

.sp -1

.IP \(bu 2.3

.\}

.\" myisamchk: wait option

.\" wait option: myisamchk

\fB\-\-wait\fR,

\fB\-w\fR

.sp

Instead of terminating with an error if the table is locked, wait until the table is unlocked before continuing\&. If you are running

\fBmysqld\fR

with external locking disabled, the table can be locked only by another

\fBmyisamchk\fR

command\&.

.RE

.PP

You can also set the following variables by using

\fB\-\-\fR\fB\fIvar_name\fR\fR\fB=\fR\fB\fIvalue\fR\fR

syntax:

.\" decode_bits myisamchk variable

.\" ft_max_word_len myisamchk variable

.\" ft_min_word_len myisamchk variable

.\" ft_stopword_file myisamchk variable

.\" key_buffer_size myisamchk variable

.\" myisam_block_size myisamchk variable

.\" read_buffer_size myisamchk variable

.\" sort_buffer_size myisamchk variable

.\" myisam_sort_buffer_size myisamchk variable

.\" sort_key_blocks myisamchk variable

.\" stats_method myisamchk variable

.\" write_buffer_size myisamchk variable

.TS

allbox tab(:);

lB lB.

T{

Variable

T}:T{

Default Value

T}

.T&

l l

l l

l l

l l

l l

l l

l l

l l

l l

l l

l l

l l.

T{

decode_bits

T}:T{

9

T}

T{

ft_max_word_len

T}:T{

version\-dependent

T}

T{

ft_min_word_len

T}:T{

4

T}

T{

ft_stopword_file

T}:T{

built\-in list

T}

T{

key_buffer_size

T}:T{

523264

T}

T{

myisam_block_size

T}:T{

1024

T}

T{

myisam_sort_key_blocks

T}:T{

16

T}

T{

read_buffer_size

T}:T{

262136

T}

T{

sort_buffer_size

T}:T{

2097144

T}

T{

sort_key_blocks

T}:T{

16

T}

T{

stats_method

T}:T{

nulls_unequal

T}

T{

write_buffer_size

T}:T{

262136

T}

.TE

.sp 1

.PP

The possible

\fBmyisamchk\fR

variables and their default values can be examined with

\fBmyisamchk \-\-help\fR:

.PP

sort_buffer_size

is used when the keys are repaired by sorting keys, which is the normal case when you use

\fB\-\-recover\fR\&. As of MySQL 5\&.6\&.9,

myisam_sort_buffer_size

is available as an alternative name to

sort_buffer_size\&.

myisam_sort_buffer_size

is preferable to

sort_buffer_size

because its name corresponds to the

myisam_sort_buffer_size

server system variable that has a similar meaning\&.

sort_buffer_size

should be considered deprecated\&.

.PP

key_buffer_size

is used when you are checking the table with

\fB\-\-extend\-check\fR

or when the keys are repaired by inserting keys row by row into the table (like when doing normal inserts)\&. Repairing through the key buffer is used in the following cases:

.sp

.RS 4

.ie n \{\

\h'-04'\(bu\h'+03'\c

.\}

.el \{\

.sp -1

.IP \(bu 2.3

.\}

You use

\fB\-\-safe\-recover\fR\&.

.RE

.sp

.RS 4

.ie n \{\

\h'-04'\(bu\h'+03'\c

.\}

.el \{\

.sp -1

.IP \(bu 2.3

.\}

The temporary files needed to sort the keys would be more than twice as big as when creating the key file directly\&. This is often the case when you have large key values for

CHAR,

VARCHAR, or

TEXT

columns, because the sort operation needs to store the complete key values as it proceeds\&. If you have lots of temporary space and you can force

\fBmyisamchk\fR

to repair by sorting, you can use the

\fB\-\-sort\-recover\fR

option\&.

.RE

.PP

Repairing through the key buffer takes much less disk space than using sorting, but is also much slower\&.

.PP

If you want a faster repair, set the

key_buffer_size

and

myisam_sort_buffer_size

variables to about 25% of your available memory\&. You can set both variables to large values, because only one of them is used at a time\&.

.PP

myisam_block_size

is the size used for index blocks\&.

.PP

stats_method

influences how

NULL

values are treated for index statistics collection when the

\fB\-\-analyze\fR

option is given\&. It acts like the

myisam_stats_method

system variable\&. For more information, see the description of

myisam_stats_method

in

Section\ \&5.1.4, \(lqServer System Variables\(rq, and

Section\ \&8.3.7, \(lqInnoDB and MyISAM Index Statistics Collection\(rq\&.

.PP

ft_min_word_len

and

ft_max_word_len

indicate the minimum and maximum word length for

FULLTEXT

indexes on

MyISAM

tables\&.

ft_stopword_file

names the stopword file\&. These need to be set under the following circumstances\&.

.PP

If you use

\fBmyisamchk\fR

to perform an operation that modifies table indexes (such as repair or analyze), the

FULLTEXT

indexes are rebuilt using the default full\-text parameter values for minimum and maximum word length and the stopword file unless you specify otherwise\&. This can result in queries failing\&.

.PP

The problem occurs because these parameters are known only by the server\&. They are not stored in

MyISAM

index files\&. To avoid the problem if you have modified the minimum or maximum word length or the stopword file in the server, specify the same

ft_min_word_len,

ft_max_word_len, and

ft_stopword_file

values to

\fBmyisamchk\fR

that you use for

\fBmysqld\fR\&. For example, if you have set the minimum word length to 3, you can repair a table with

\fBmyisamchk\fR

like this:

.sp

.if n \{\

.RS 4

.\}

.nf

shell> \fBmyisamchk \-\-recover \-\-ft_min_word_len=3 \fR\fB\fItbl_name\fR\fR\fB\&.MYI\fR

.fi

.if n \{\

.RE

.\}

.PP

To ensure that

\fBmyisamchk\fR

and the server use the same values for full\-text parameters, you can place each one in both the

[mysqld]

and

[myisamchk]

sections of an option file:

.sp

.if n \{\

.RS 4

.\}

.nf

[mysqld]

ft_min_word_len=3

[myisamchk]

ft_min_word_len=3

.fi

.if n \{\

.RE

.\}

.PP

An alternative to using

\fBmyisamchk\fR

is to use the

REPAIR TABLE,

ANALYZE TABLE,

OPTIMIZE TABLE, or

ALTER TABLE\&. These statements are performed by the server, which knows the proper full\-text parameter values to use\&.

.SH "MYISAMCHK CHECK OPTIONS"

.\" check options: myisamchk

.\" tables: checking

.PP

\fBmyisamchk\fR

supports the following options for table checking operations:

.sp

.RS 4

.ie n \{\

\h'-04'\(bu\h'+03'\c

.\}

.el \{\

.sp -1

.IP \(bu 2.3

.\}

.\" myisamchk: check option

.\" check option: myisamchk

\fB\-\-check\fR,

\fB\-c\fR

.sp

Check the table for errors\&. This is the default operation if you specify no option that selects an operation type explicitly\&.

.RE

.sp

.RS 4

.ie n \{\

\h'-04'\(bu\h'+03'\c

.\}

.el \{\

.sp -1

.IP \(bu 2.3

.\}

.\" myisamchk: check-only-changed option

.\" check-only-changed option: myisamchk

\fB\-\-check\-only\-changed\fR,

\fB\-C\fR

.sp

Check only tables that have changed since the last check\&.

.RE

.sp

.RS 4

.ie n \{\

\h'-04'\(bu\h'+03'\c

.\}

.el \{\

.sp -1

.IP \(bu 2.3

.\}

.\" myisamchk: extend-check option

.\" extend-check option: myisamchk

\fB\-\-extend\-check\fR,

\fB\-e\fR

.sp

Check the table very thoroughly\&. This is quite slow if the table has many indexes\&. This option should only be used in extreme cases\&. Normally,

\fBmyisamchk\fR

or

\fBmyisamchk \-\-medium\-check\fR

should be able to determine whether there are any errors in the table\&.

.sp

If you are using

\fB\-\-extend\-check\fR

and have plenty of memory, setting the

key_buffer_size

variable to a large value helps the repair operation run faster\&.

.sp

See also the description of this option under table repair options\&.

.sp

For a description of the output format, see

the section called \(lqOBTAINING TABLE INFORMATION WITH MYISAMCHK\(rq\&.

.RE

.sp

.RS 4

.ie n \{\

\h'-04'\(bu\h'+03'\c

.\}

.el \{\

.sp -1

.IP \(bu 2.3

.\}

.\" myisamchk: fast option

.\" fast option: myisamchk

\fB\-\-fast\fR,

\fB\-F\fR

.sp

Check only tables that haven\*(Aqt been closed properly\&.

.RE

.sp

.RS 4

.ie n \{\

\h'-04'\(bu\h'+03'\c

.\}

.el \{\

.sp -1

.IP \(bu 2.3

.\}

.\" myisamchk: force option

.\" force option: myisamchk

\fB\-\-force\fR,

\fB\-f\fR

.sp

Do a repair operation automatically if

\fBmyisamchk\fR

finds any errors in the table\&. The repair type is the same as that specified with the

\fB\-\-recover\fR

or

\fB\-r\fR

option\&.

.RE

.sp

.RS 4

.ie n \{\

\h'-04'\(bu\h'+03'\c

.\}

.el \{\

.sp -1

.IP \(bu 2.3

.\}

.\" myisamchk: information option

.\" information option: myisamchk

\fB\-\-information\fR,

\fB\-i\fR

.sp

Print informational statistics about the table that is checked\&.

.RE

.sp

.RS 4

.ie n \{\

\h'-04'\(bu\h'+03'\c

.\}

.el \{\

.sp -1

.IP \(bu 2.3

.\}

.\" myisamchk: medium-check option

.\" medium-check option: myisamchk

\fB\-\-medium\-check\fR,

\fB\-m\fR

.sp

Do a check that is faster than an

\fB\-\-extend\-check\fR

operation\&. This finds only 99\&.99% of all errors, which should be good enough in most cases\&.

.RE

.sp

.RS 4

.ie n \{\

\h'-04'\(bu\h'+03'\c

.\}

.el \{\

.sp -1

.IP \(bu 2.3

.\}

.\" myisamchk: read-only option

.\" read-only option: myisamchk

\fB\-\-read\-only\fR,

\fB\-T\fR

.sp

Do not mark the table as checked\&. This is useful if you use

\fBmyisamchk\fR

to check a table that is in use by some other application that does not use locking, such as

\fBmysqld\fR

when run with external locking disabled\&.

.RE

.sp

.RS 4

.ie n \{\

\h'-04'\(bu\h'+03'\c

.\}

.el \{\

.sp -1

.IP \(bu 2.3

.\}

.\" myisamchk: update-state option

.\" update-state option: myisamchk

\fB\-\-update\-state\fR,

\fB\-U\fR

.sp

Store information in the

\&.MYI

file to indicate when the table was checked and whether the table crashed\&. This should be used to get full benefit of the

\fB\-\-check\-only\-changed\fR

option, but you shouldn\*(Aqt use this option if the

\fBmysqld\fR

server is using the table and you are running it with external locking disabled\&.

.RE

.SH "MYISAMCHK REPAIR OPTIONS"

.\" repair options: myisamchk

.\" files: repairing

.PP

\fBmyisamchk\fR

supports the following options for table repair operations (operations performed when an option such as

\fB\-\-recover\fR

or

\fB\-\-safe\-recover\fR

is given):

.sp

.RS 4

.ie n \{\

\h'-04'\(bu\h'+03'\c

.\}

.el \{\

.sp -1

.IP \(bu 2.3

.\}

.\" myisamchk: backup option

.\" backup option: myisamchk

\fB\-\-backup\fR,

\fB\-B\fR

.sp

Make a backup of the

\&.MYD

file as

\fIfile_name\fR\-\fItime\fR\&.BAK

.RE

.sp

.RS 4

.ie n \{\

\h'-04'\(bu\h'+03'\c

.\}

.el \{\

.sp -1

.IP \(bu 2.3

.\}

.\" myisamchk: character-sets-dir option

.\" character-sets-dir option: myisamchk

\fB\-\-character\-sets\-dir=\fR\fB\fIpath\fR\fR

.sp

The directory where character sets are installed\&. See

Section\ \&10.5, \(lqCharacter Set Configuration\(rq\&.

.RE

.sp

.RS 4

.ie n \{\

\h'-04'\(bu\h'+03'\c

.\}

.el \{\

.sp -1

.IP \(bu 2.3

.\}

.\" myisamchk: correct-checksum option

.\" correct-checksum option: myisamchk

\fB\-\-correct\-checksum\fR

.sp

Correct the checksum information for the table\&.

.RE

.sp

.RS 4

.ie n \{\

\h'-04'\(bu\h'+03'\c

.\}

.el \{\

.sp -1

.IP \(bu 2.3

.\}

.\" myisamchk: data-file-length option

.\" data-file-length option: myisamchk

\fB\-\-data\-file\-length=\fR\fB\fIlen\fR\fR,

\fB\-D \fR\fB\fIlen\fR\fR

.sp

The maximum length of the data file (when re\-creating data file when it is

\(lqfull\(rq)\&.

.RE

.sp

.RS 4

.ie n \{\

\h'-04'\(bu\h'+03'\c

.\}

.el \{\

.sp -1

.IP \(bu 2.3

.\}

.\" myisamchk: extend-check option

.\" extend-check option: myisamchk

\fB\-\-extend\-check\fR,

\fB\-e\fR

.sp

Do a repair that tries to recover every possible row from the data file\&. Normally, this also finds a lot of garbage rows\&. Do not use this option unless you are desperate\&.

.sp

See also the description of this option under table checking options\&.

.sp

For a description of the output format, see

the section called \(lqOBTAINING TABLE INFORMATION WITH MYISAMCHK\(rq\&.

.RE

.sp

.RS 4

.ie n \{\

\h'-04'\(bu\h'+03'\c