2507 lines
51 KiB
Groff
2507 lines
51 KiB
Groff
'\" t
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.\" Title: \fBmyisamchk\fR
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.\" Author: [FIXME: author] [see http://docbook.sf.net/el/author]
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.\" Generator: DocBook XSL Stylesheets v1.77.1 <http://docbook.sf.net/>
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.\" Date: 11/04/2013
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.\" Manual: MySQL Database System
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.\" Source: MySQL 5.1
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.\" Language: English
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.\"
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.TH "\FBMYISAMCHK\FR" "1" "11/04/2013" "MySQL 5\&.1" "MySQL Database System"
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.\" -----------------------------------------------------------------
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.\" * Define some portability stuff
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.\" -----------------------------------------------------------------
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.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.\" http://bugs.debian.org/507673
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.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
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.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.ie \n(.g .ds Aq \(aq
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.el .ds Aq '
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.\" -----------------------------------------------------------------
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.\" * set default formatting
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.\" -----------------------------------------------------------------
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.\" disable hyphenation
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.nh
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.\" disable justification (adjust text to left margin only)
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.ad l
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.\" -----------------------------------------------------------------
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.\" * MAIN CONTENT STARTS HERE *
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.\" -----------------------------------------------------------------
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.\" myisamchk
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.SH "NAME"
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myisamchk \- MyISAM table\-maintenance utility
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.SH "SYNOPSIS"
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.HP \w'\fBmyisamchk\ [\fR\fB\fIoptions\fR\fR\fB]\ \fR\fB\fItbl_name\fR\fR\fB\ \&.\&.\&.\fR\ 'u
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\fBmyisamchk [\fR\fB\fIoptions\fR\fR\fB] \fR\fB\fItbl_name\fR\fR\fB \&.\&.\&.\fR
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.SH "DESCRIPTION"
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.PP
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The
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\fBmyisamchk\fR
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utility gets information about your database tables or checks, repairs, or optimizes them\&.
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\fBmyisamchk\fR
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works with
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MyISAM
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tables (tables that have
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\&.MYD
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and
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\&.MYI
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files for storing data and indexes)\&.
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.PP
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You can also use the
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CHECK TABLE
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and
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REPAIR TABLE
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statements to check and repair
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MyISAM
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tables\&. See
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Section\ \&13.7.2.3, \(lqCHECK TABLE Syntax\(rq, and
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Section\ \&13.7.2.6, \(lqREPAIR TABLE Syntax\(rq\&.
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.PP
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The use of
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\fBmyisamchk\fR
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with partitioned tables is not supported\&.
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.if n \{\
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.sp
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.\}
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.RS 4
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.it 1 an-trap
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.nr an-no-space-flag 1
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.nr an-break-flag 1
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.br
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.ps +1
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\fBCaution\fR
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.ps -1
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.br
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.PP
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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\&.
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.sp .5v
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.RE
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.PP
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Invoke
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\fBmyisamchk\fR
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like this:
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.sp
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.if n \{\
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.RS 4
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.\}
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.nf
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shell> \fBmyisamchk [\fR\fB\fIoptions\fR\fR\fB] \fR\fB\fItbl_name\fR\fR\fB \&.\&.\&.\fR
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.fi
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.if n \{\
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.RE
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.\}
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.PP
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The
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\fIoptions\fR
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specify what you want
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\fBmyisamchk\fR
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to do\&. They are described in the following sections\&. You can also get a list of options by invoking
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\fBmyisamchk \-\-help\fR\&.
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.PP
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With no options,
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\fBmyisamchk\fR
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simply checks your table as the default operation\&. To get more information or to tell
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\fBmyisamchk\fR
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to take corrective action, specify options as described in the following discussion\&.
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.PP
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\fItbl_name\fR
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is the database table you want to check or repair\&. If you run
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\fBmyisamchk\fR
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somewhere other than in the database directory, you must specify the path to the database directory, because
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\fBmyisamchk\fR
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has no idea where the database is located\&. In fact,
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\fBmyisamchk\fR
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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\&.
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.PP
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You can name several tables on the
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\fBmyisamchk\fR
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command line if you wish\&. You can also specify a table by naming its index file (the file with the
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\&.MYI
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suffix)\&. This enables you to specify all tables in a directory by using the pattern
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*\&.MYI\&. For example, if you are in a database directory, you can check all the
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MyISAM
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tables in that directory like this:
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.sp
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.if n \{\
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.RS 4
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.\}
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.nf
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shell> \fBmyisamchk *\&.MYI\fR
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.fi
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.if n \{\
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.RE
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.\}
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.PP
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If you are not in the database directory, you can check all the tables there by specifying the path to the directory:
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.sp
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.if n \{\
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.RS 4
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.\}
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.nf
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shell> \fBmyisamchk \fR\fB\fI/path/to/database_dir/\fR\fR\fB*\&.MYI\fR
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.fi
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.if n \{\
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.RE
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.\}
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.PP
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You can even check all tables in all databases by specifying a wildcard with the path to the MySQL data directory:
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.sp
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.if n \{\
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.RS 4
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.\}
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.nf
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shell> \fBmyisamchk \fR\fB\fI/path/to/datadir/*/*\fR\fR\fB\&.MYI\fR
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.fi
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.if n \{\
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.RE
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.\}
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.PP
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The recommended way to quickly check all
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MyISAM
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tables is:
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.sp
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.if n \{\
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.RS 4
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.\}
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.nf
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shell> \fBmyisamchk \-\-silent \-\-fast \fR\fB\fI/path/to/datadir/*/*\fR\fR\fB\&.MYI\fR
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.fi
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.if n \{\
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.RE
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.\}
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.PP
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If you want to check all
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MyISAM
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tables and repair any that are corrupted, you can use the following command:
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.sp
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.if n \{\
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.RS 4
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.\}
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.nf
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shell> \fBmyisamchk \-\-silent \-\-force \-\-fast \-\-update\-state \e\fR
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\fB\-\-key_buffer_size=64M \-\-myisam_sort_buffer_size=64M \e\fR
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\fB\-\-read_buffer_size=1M \-\-write_buffer_size=1M \e\fR
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\fB\fI/path/to/datadir/*/*\fR\fR\fB\&.MYI\fR
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.fi
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.if n \{\
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.RE
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.\}
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.PP
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This command assumes that you have more than 64MB free\&. For more information about memory allocation with
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\fBmyisamchk\fR, see
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the section called \(lqMYISAMCHK MEMORY USAGE\(rq\&.
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.PP
|
|
For additional information about using
|
|
\fBmyisamchk\fR, see
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Section\ \&7.6, \(lqMyISAM Table Maintenance and Crash Recovery\(rq\&.
|
|
.if n \{\
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.sp
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|
.\}
|
|
.RS 4
|
|
.it 1 an-trap
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.nr an-no-space-flag 1
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|
.nr an-break-flag 1
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.br
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.ps +1
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\fBImportant\fR
|
|
.ps -1
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.br
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.PP
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|
\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
|
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\fBmyisamchk\fR, or to lock all tables that
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\fBmyisamchk\fR
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is being used on\&.
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.PP
|
|
Otherwise, when you run
|
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\fBmyisamchk\fR, it may display the following error message:
|
|
.sp
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.if n \{\
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.RS 4
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.\}
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|
.nf
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|
warning: clients are using or haven\*(Aqt closed the table properly
|
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.fi
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.if n \{\
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.RE
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.\}
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.PP
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|
This means that you are trying to check a table that has been updated by another program (such as the
|
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\fBmysqld\fR
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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
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tables\&.
|
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.PP
|
|
If
|
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\fBmysqld\fR
|
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is running, you must force it to flush any table modifications that are still buffered in memory by using
|
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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
|
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CHECK TABLE
|
|
instead of
|
|
\fBmyisamchk\fR
|
|
to check tables\&. See
|
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Section\ \&13.7.2.3, \(lqCHECK TABLE Syntax\(rq\&.
|
|
.sp .5v
|
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.RE
|
|
.PP
|
|
\fBmyisamchk\fR
|
|
supports the following options, which can be specified on the command line or in the
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[myisamchk]
|
|
group of an option file\&.
|
|
\fBmyisamchk\fR
|
|
also supports the options for processing option files described at
|
|
Section\ \&4.2.3.4, \(lqCommand-Line Options that Affect Option-File Handling\(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
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.RS 4
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|
.ie n \{\
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|
\h'-04'\(bu\h'+03'\c
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|
.\}
|
|
.el \{\
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|
.sp -1
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|
.IP \(bu 2.3
|
|
.\}
|
|
.\" myisamchk: help option
|
|
.\" help option: myisamchk
|
|
\fB\-\-help\fR,
|
|
\fB\-?\fR
|
|
.sp
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|
Display a help message and exit\&. Options are grouped by type of operation\&.
|
|
.RE
|
|
.sp
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.RS 4
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.ie n \{\
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\h'-04'\(bu\h'+03'\c
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|
.\}
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|
.el \{\
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|
.sp -1
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|
.IP \(bu 2.3
|
|
.\}
|
|
.\" myisamchk: HELP option
|
|
.\" HELP option: myisamchk
|
|
\fB\-\-HELP\fR,
|
|
\fB\-H\fR
|
|
.sp
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|
Display a help message and exit\&. Options are presented in a single list\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
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\h'-04'\(bu\h'+03'\c
|
|
.\}
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|
.el \{\
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|
.sp -1
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.IP \(bu 2.3
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|
.\}
|
|
.\" myisamchk: debug option
|
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.\" debug option: myisamchk
|
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\fB\-\-debug=\fR\fB\fIdebug_options\fR\fR,
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\fB\-# \fR\fB\fIdebug_options\fR\fR
|
|
.sp
|
|
Write a debugging log\&. A typical
|
|
\fIdebug_options\fR
|
|
string is
|
|
\*(Aqd:t:o,\fIfile_name\fR\*(Aq\&. The default is
|
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\*(Aqd:t:o,/tmp/myisamchk\&.trace\*(Aq\&.
|
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.RE
|
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.sp
|
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.RS 4
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.ie n \{\
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\h'-04'\(bu\h'+03'\c
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.\}
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.el \{\
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.sp -1
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.IP \(bu 2.3
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.\}
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.\" myisamchk: silent option
|
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.\" silent option: myisamchk
|
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\fB\-\-silent\fR,
|
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\fB\-s\fR
|
|
.sp
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|
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
|
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.sp
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|
.RS 4
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|
.ie n \{\
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\h'-04'\(bu\h'+03'\c
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.\}
|
|
.el \{\
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.sp -1
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|
.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 \{\
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|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
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|
.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 \{\
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|
\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\&.1\&.67,
|
|
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\ \&8.5.4, \(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\&.
|
|
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
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
.\" myisamchk: force option
|
|
.\" force option: myisamchk
|
|
\fB\-\-force\fR,
|
|
\fB\-f\fR
|
|
.sp
|
|
Overwrite old intermediate files (files with names like
|
|
\fItbl_name\fR\&.TMD) instead of aborting\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
.\" myisamchk: keys-used option
|
|
.\" keys-used option: myisamchk
|
|
\fB\-\-keys\-used=\fR\fB\fIval\fR\fR,
|
|
\fB\-k \fR\fB\fIval\fR\fR
|
|
.sp
|
|
For
|
|
\fBmyisamchk\fR, the option value is a bit\-value that indicates which indexes to update\&. Each binary bit of the option value corresponds to a table index, where the first index is bit 0\&. An option value of 0 disables updates to all indexes, which can be used to get faster inserts\&. Deactivated indexes can be reactivated by using
|
|
\fBmyisamchk \-r\fR\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
.\" myisamchk: no-symlinks option
|
|
.\" no-symlinks option: myisamchk
|
|
\fB\-\-no\-symlinks\fR,
|
|
\fB\-l\fR
|
|
.sp
|
|
Do not follow symbolic links\&. Normally
|
|
\fBmyisamchk\fR
|
|
repairs the table that a symlink points to\&. This option does not exist as of MySQL 4\&.0 because versions from 4\&.0 on do not remove symlinks during repair operations\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
.\" myisamchk: max-record-length option
|
|
.\" max-record-length option: myisamchk
|
|
\fB\-\-max\-record\-length=\fR\fB\fIlen\fR\fR
|
|
.sp
|
|
Skip rows larger than the given length if
|
|
\fBmyisamchk\fR
|
|
cannot allocate memory to hold them\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
.\" myisamchk: parallel-recover option
|
|
.\" parallel-recover option: myisamchk
|
|
\fB\-\-parallel\-recover\fR,
|
|
\fB\-p\fR
|
|
.sp
|
|
Use the same technique as
|
|
\fB\-r\fR
|
|
and
|
|
\fB\-n\fR, but create all the keys in parallel, using different threads\&.
|
|
\fIThis is beta\-quality code\&. Use at your own risk!\fR
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
.\" myisamchk: quick option
|
|
.\" quick option: myisamchk
|
|
\fB\-\-quick\fR,
|
|
\fB\-q\fR
|
|
.sp
|
|
Achieve a faster repair by modifying only the index file, not the data file\&. You can specify this option twice to force
|
|
\fBmyisamchk\fR
|
|
to modify the original data file in case of duplicate keys\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
.\" myisamchk: recover option
|
|
.\" recover option: myisamchk
|
|
\fB\-\-recover\fR,
|
|
\fB\-r\fR
|
|
.sp
|
|
Do a repair that can fix almost any problem except unique keys that are not unique (which is an extremely unlikely error with
|
|
MyISAM
|
|
tables)\&. If you want to recover a table, this is the option to try first\&. You should try
|
|
\fB\-\-safe\-recover\fR
|
|
only if
|
|
\fBmyisamchk\fR
|
|
reports that the table cannot be recovered using
|
|
\fB\-\-recover\fR\&. (In the unlikely case that
|
|
\fB\-\-recover\fR
|
|
fails, the data file remains intact\&.)
|
|
.sp
|
|
If you have lots of memory, you should increase the value of
|
|
myisam_sort_buffer_size\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
.\" myisamchk: safe-recover option
|
|
.\" safe-recover option: myisamchk
|
|
\fB\-\-safe\-recover\fR,
|
|
\fB\-o\fR
|
|
.sp
|
|
Do a repair using an old recovery method that reads through all rows in order and updates all index trees based on the rows found\&. This is an order of magnitude slower than
|
|
\fB\-\-recover\fR, but can handle a couple of very unlikely cases that
|
|
\fB\-\-recover\fR
|
|
cannot\&. This recovery method also uses much less disk space than
|
|
\fB\-\-recover\fR\&. Normally, you should repair first using
|
|
\fB\-\-recover\fR, and then with
|
|
\fB\-\-safe\-recover\fR
|
|
only if
|
|
\fB\-\-recover\fR
|
|
fails\&.
|
|
.sp
|
|
If you have lots of memory, you should increase the value of
|
|
key_buffer_size\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
.\" myisamchk: set-character-set option
|
|
.\" set-character-set option: myisamchk
|
|
\fB\-\-set\-character\-set=\fR\fB\fIname\fR\fR
|
|
.sp
|
|
Change the character set used by the table indexes\&. This option was replaced by
|
|
\fB\-\-set\-collation\fR
|
|
in MySQL 5\&.0\&.3\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
.\" myisamchk: set-collation option
|
|
.\" set-collation option: myisamchk
|
|
\fB\-\-set\-collation=\fR\fB\fIname\fR\fR
|
|
.sp
|
|
Specify the collation to use for sorting table indexes\&. The character set name is implied by the first part of the collation name\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
.\" myisamchk: sort-recover option
|
|
.\" sort-recover option: myisamchk
|
|
\fB\-\-sort\-recover\fR,
|
|
\fB\-n\fR
|
|
.sp
|
|
Force
|
|
\fBmyisamchk\fR
|
|
to use sorting to resolve the keys even if the temporary files would be very large\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
.\" myisamchk: tmpdir option
|
|
.\" tmpdir option: myisamchk
|
|
\fB\-\-tmpdir=\fR\fB\fIpath\fR\fR,
|
|
\fB\-t \fR\fB\fIpath\fR\fR
|
|
.sp
|
|
The path of the directory to be used for storing temporary files\&. If this is not set,
|
|
\fBmyisamchk\fR
|
|
uses the value of the
|
|
TMPDIR
|
|
environment variable\&.
|
|
\fB\-\-tmpdir\fR
|
|
can be set to a list of directory paths that are used successively in round\-robin fashion for creating temporary files\&. The separator character between directory names is the colon (\(lq:\(rq) on Unix and the semicolon (\(lq;\(rq) on Windows, NetWare, and OS/2\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
.\" myisamchk: unpack option
|
|
.\" unpack option: myisamchk
|
|
\fB\-\-unpack\fR,
|
|
\fB\-u\fR
|
|
.sp
|
|
Unpack a table that was packed with
|
|
\fBmyisampack\fR\&.
|
|
.RE
|
|
.SH "OTHER MYISAMCHK OPTIONS"
|
|
.PP
|
|
\fBmyisamchk\fR
|
|
supports the following options for actions other than table checks and repairs:
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
.\" myisamchk: analyze option
|
|
.\" analyze option: myisamchk
|
|
\fB\-\-analyze\fR,
|
|
\fB\-a\fR
|
|
.sp
|
|
Analyze the distribution of key values\&. This improves join performance by enabling the join optimizer to better choose the order in which to join the tables and which indexes it should use\&. To obtain information about the key distribution, use a
|
|
\fBmyisamchk \-\-description \-\-verbose \fR\fB\fItbl_name\fR\fR
|
|
command or the
|
|
SHOW INDEX FROM \fItbl_name\fR
|
|
statement\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
.\" myisamchk: block-search option
|
|
.\" block-search option: myisamchk
|
|
\fB\-\-block\-search=\fR\fB\fIoffset\fR\fR,
|
|
\fB\-b \fR\fB\fIoffset\fR\fR
|
|
.sp
|
|
Find the record that a block at the given offset belongs to\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
.\" myisamchk: description option
|
|
.\" description option: myisamchk
|
|
\fB\-\-description\fR,
|
|
\fB\-d\fR
|
|
.sp
|
|
Print some descriptive information about the table\&. Specifying the
|
|
\fB\-\-verbose\fR
|
|
option once or twice produces additional information\&. 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: set-auto-increment[ option
|
|
.\" set-auto-increment[ option: myisamchk
|
|
\fB\-\-set\-auto\-increment[=\fR\fB\fIvalue\fR\fR\fB]\fR,
|
|
\fB\-A[\fR\fB\fIvalue\fR\fR\fB]\fR
|
|
.sp
|
|
Force
|
|
AUTO_INCREMENT
|
|
numbering for new records to start at the given value (or higher, if there are existing records with
|
|
AUTO_INCREMENT
|
|
values this large)\&. If
|
|
\fIvalue\fR
|
|
is not specified,
|
|
AUTO_INCREMENT
|
|
numbers for new records begin with the largest value currently in the table, plus one\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
.\" myisamchk: sort-index option
|
|
.\" sort-index option: myisamchk
|
|
\fB\-\-sort\-index\fR,
|
|
\fB\-S\fR
|
|
.sp
|
|
Sort the index tree blocks in high\-low order\&. This optimizes seeks and makes table scans that use indexes faster\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
.\" myisamchk: sort-records option
|
|
.\" sort-records option: myisamchk
|
|
\fB\-\-sort\-records=\fR\fB\fIN\fR\fR,
|
|
\fB\-R \fR\fB\fIN\fR\fR
|
|
.sp
|
|
Sort records according to a particular index\&. This makes your data much more localized and may speed up range\-based
|
|
SELECT
|
|
and
|
|
ORDER BY
|
|
operations that use this index\&. (The first time you use this option to sort a table, it may be very slow\&.) To determine a table\*(Aqs index numbers, use
|
|
SHOW INDEX, which displays a table\*(Aqs indexes in the same order that
|
|
\fBmyisamchk\fR
|
|
sees them\&. Indexes are numbered beginning with 1\&.
|
|
.sp
|
|
If keys are not packed (PACK_KEYS=0), they have the same length, so when
|
|
\fBmyisamchk\fR
|
|
sorts and moves records, it just overwrites record offsets in the index\&. If keys are packed (PACK_KEYS=1),
|
|
\fBmyisamchk\fR
|
|
must unpack key blocks first, then re\-create indexes and pack the key blocks again\&. (In this case, re\-creating indexes is faster than updating offsets for each index\&.)
|
|
.RE
|
|
.SH "OBTAINING TABLE INFORMATION WITH MYISAMCHK"
|
|
.\" table description: myisamchk
|
|
.\" tables: information
|
|
.\" examples: myisamchk output
|
|
.\" myisamchk: example output
|
|
.PP
|
|
To obtain a description of a
|
|
MyISAM
|
|
table or statistics about it, use the commands shown here\&. The output from these commands is explained later in this section\&.
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
\fBmyisamchk \-d \fR\fB\fItbl_name\fR\fR
|
|
.sp
|
|
Runs
|
|
\fBmyisamchk\fR
|
|
in
|
|
\(lqdescribe mode\(rq
|
|
to produce a description of your table\&. If you start the MySQL server with external locking disabled,
|
|
\fBmyisamchk\fR
|
|
may report an error for a table that is updated while it runs\&. However, because
|
|
\fBmyisamchk\fR
|
|
does not change the table in describe mode, there is no risk of destroying data\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
\fBmyisamchk \-dv \fR\fB\fItbl_name\fR\fR
|
|
.sp
|
|
Adding
|
|
\fB\-v\fR
|
|
runs
|
|
\fBmyisamchk\fR
|
|
in verbose mode so that it produces more information about the table\&. Adding
|
|
\fB\-v\fR
|
|
a second time produces even more information\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
\fBmyisamchk \-eis \fR\fB\fItbl_name\fR\fR
|
|
.sp
|
|
Shows only the most important information from a table\&. This operation is slow because it must read the entire table\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
\fBmyisamchk \-eiv \fR\fB\fItbl_name\fR\fR
|
|
.sp
|
|
This is like
|
|
\fB\-eis\fR, but tells you what is being done\&.
|
|
.RE
|
|
.PP
|
|
The
|
|
\fItbl_name\fR
|
|
argument can be either the name of a
|
|
MyISAM
|
|
table or the name of its index file, as described in
|
|
\fBmyisamchk\fR(1)\&. Multiple
|
|
\fItbl_name\fR
|
|
arguments can be given\&.
|
|
.PP
|
|
Suppose that a table named
|
|
person
|
|
has the following structure\&. (The
|
|
MAX_ROWS
|
|
table option is included so that in the example output from
|
|
\fBmyisamchk\fR
|
|
shown later, some values are smaller and fit the output format more easily\&.)
|
|
.sp
|
|
.if n \{\
|
|
.RS 4
|
|
.\}
|
|
.nf
|
|
CREATE TABLE person
|
|
(
|
|
id INT NOT NULL AUTO_INCREMENT,
|
|
last_name VARCHAR(20) NOT NULL,
|
|
first_name VARCHAR(20) NOT NULL,
|
|
birth DATE,
|
|
death DATE,
|
|
PRIMARY KEY (id),
|
|
INDEX (last_name, first_name),
|
|
INDEX (birth)
|
|
) MAX_ROWS = 1000000;
|
|
.fi
|
|
.if n \{\
|
|
.RE
|
|
.\}
|
|
.PP
|
|
Suppose also that the table has these data and index file sizes:
|
|
.sp
|
|
.if n \{\
|
|
.RS 4
|
|
.\}
|
|
.nf
|
|
\-rw\-rw\-\-\-\- 1 mysql mysql 9347072 Aug 19 11:47 person\&.MYD
|
|
\-rw\-rw\-\-\-\- 1 mysql mysql 6066176 Aug 19 11:47 person\&.MYI
|
|
.fi
|
|
.if n \{\
|
|
.RE
|
|
.\}
|
|
.PP
|
|
Example of
|
|
\fBmyisamchk \-dvv\fR
|
|
output:
|
|
.sp
|
|
.if n \{\
|
|
.RS 4
|
|
.\}
|
|
.nf
|
|
MyISAM file: person
|
|
Record format: Packed
|
|
Character set: latin1_swedish_ci (8)
|
|
File\-version: 1
|
|
Creation time: 2009\-08\-19 16:47:41
|
|
Recover time: 2009\-08\-19 16:47:56
|
|
Status: checked,analyzed,optimized keys
|
|
Auto increment key: 1 Last value: 306688
|
|
Data records: 306688 Deleted blocks: 0
|
|
Datafile parts: 306688 Deleted data: 0
|
|
Datafile pointer (bytes): 4 Keyfile pointer (bytes): 3
|
|
Datafile length: 9347072 Keyfile length: 6066176
|
|
Max datafile length: 4294967294 Max keyfile length: 17179868159
|
|
Recordlength: 54
|
|
table description:
|
|
Key Start Len Index Type Rec/key Root Blocksize
|
|
1 2 4 unique long 1 99328 1024
|
|
2 6 20 multip\&. varchar prefix 512 3563520 1024
|
|
27 20 varchar 512
|
|
3 48 3 multip\&. uint24 NULL 306688 6065152 1024
|
|
Field Start Length Nullpos Nullbit Type
|
|
1 1 1
|
|
2 2 4 no zeros
|
|
3 6 21 varchar
|
|
4 27 21 varchar
|
|
5 48 3 1 1 no zeros
|
|
6 51 3 1 2 no zeros
|
|
.fi
|
|
.if n \{\
|
|
.RE
|
|
.\}
|
|
.PP
|
|
Explanations for the types of information
|
|
\fBmyisamchk\fR
|
|
produces are given here\&.
|
|
\(lqKeyfile\(rq
|
|
refers to the index file\&.
|
|
\(lqRecord\(rq
|
|
and
|
|
\(lqrow\(rq
|
|
are synonymous, as are
|
|
\(lqfield\(rq
|
|
and
|
|
\(lqcolumn\&.\(rq
|
|
.PP
|
|
The initial part of the table description contains these values:
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
MyISAM file
|
|
.sp
|
|
Name of the
|
|
MyISAM
|
|
(index) file\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Record format
|
|
.sp
|
|
The format used to store table rows\&. The preceding examples use
|
|
Fixed length\&. Other possible values are
|
|
Compressed
|
|
and
|
|
Packed\&. (Packed
|
|
corresponds to what
|
|
SHOW TABLE STATUS
|
|
reports as
|
|
Dynamic\&.)
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Chararacter set
|
|
.sp
|
|
The table default character set\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
File\-version
|
|
.sp
|
|
Version of
|
|
MyISAM
|
|
format\&. Currently always 1\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Creation time
|
|
.sp
|
|
When the data file was created\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Recover time
|
|
.sp
|
|
When the index/data file was last reconstructed\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Status
|
|
.sp
|
|
Table status flags\&. Possible values are
|
|
crashed,
|
|
open,
|
|
changed,
|
|
analyzed,
|
|
optimized keys, and
|
|
sorted index pages\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Auto increment key,
|
|
Last value
|
|
.sp
|
|
The key number associated the table\*(Aqs
|
|
AUTO_INCREMENT
|
|
column, and the most recently generated value for this column\&. These fields do not appear if there is no such column\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Data records
|
|
.sp
|
|
The number of rows in the table\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Deleted blocks
|
|
.sp
|
|
How many deleted blocks still have reserved space\&. You can optimize your table to minimize this space\&. See
|
|
Section\ \&7.6.4, \(lqMyISAM Table Optimization\(rq\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Datafile parts
|
|
.sp
|
|
For dynamic\-row format, this indicates how many data blocks there are\&. For an optimized table without fragmented rows, this is the same as
|
|
Data records\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Deleted data
|
|
.sp
|
|
How many bytes of unreclaimed deleted data there are\&. You can optimize your table to minimize this space\&. See
|
|
Section\ \&7.6.4, \(lqMyISAM Table Optimization\(rq\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Datafile pointer
|
|
.sp
|
|
The size of the data file pointer, in bytes\&. It is usually 2, 3, 4, or 5 bytes\&. Most tables manage with 2 bytes, but this cannot be controlled from MySQL yet\&. For fixed tables, this is a row address\&. For dynamic tables, this is a byte address\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Keyfile pointer
|
|
.sp
|
|
The size of the index file pointer, in bytes\&. It is usually 1, 2, or 3 bytes\&. Most tables manage with 2 bytes, but this is calculated automatically by MySQL\&. It is always a block address\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Max datafile length
|
|
.sp
|
|
How long the table data file can become, in bytes\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Max keyfile length
|
|
.sp
|
|
How long the table index file can become, in bytes\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Recordlength
|
|
.sp
|
|
How much space each row takes, in bytes\&.
|
|
.RE
|
|
.PP
|
|
The
|
|
table description
|
|
part of the output includes a list of all keys in the table\&. For each key,
|
|
\fBmyisamchk\fR
|
|
displays some low\-level information:
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Key
|
|
.sp
|
|
This key\*(Aqs number\&. This value is shown only for the first column of the key\&. If this value is missing, the line corresponds to the second or later column of a multiple\-column key\&. For the table shown in the example, there are two
|
|
table description
|
|
lines for the second index\&. This indicates that it is a multiple\-part index with two parts\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Start
|
|
.sp
|
|
Where in the row this portion of the index starts\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Len
|
|
.sp
|
|
How long this portion of the index is\&. For packed numbers, this should always be the full length of the column\&. For strings, it may be shorter than the full length of the indexed column, because you can index a prefix of a string column\&. The total length of a multiple\-part key is the sum of the
|
|
Len
|
|
values for all key parts\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Index
|
|
.sp
|
|
Whether a key value can exist multiple times in the index\&. Possible values are
|
|
unique
|
|
or
|
|
multip\&.
|
|
(multiple)\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Type
|
|
.sp
|
|
What data type this portion of the index has\&. This is a
|
|
MyISAM
|
|
data type with the possible values
|
|
packed,
|
|
stripped, or
|
|
empty\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Root
|
|
.sp
|
|
Address of the root index block\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Blocksize
|
|
.sp
|
|
The size of each index block\&. By default this is 1024, but the value may be changed at compile time when MySQL is built from source\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Rec/key
|
|
.sp
|
|
This is a statistical value used by the optimizer\&. It tells how many rows there are per value for this index\&. A unique index always has a value of 1\&. This may be updated after a table is loaded (or greatly changed) with
|
|
\fBmyisamchk \-a\fR\&. If this is not updated at all, a default value of 30 is given\&.
|
|
.RE
|
|
.PP
|
|
The last part of the output provides information about each column:
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Field
|
|
.sp
|
|
The column number\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Start
|
|
.sp
|
|
The byte position of the column within table rows\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Length
|
|
.sp
|
|
The length of the column in bytes\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Nullpos,
|
|
Nullbit
|
|
.sp
|
|
For columns that can be
|
|
NULL,
|
|
MyISAM
|
|
stores
|
|
NULL
|
|
values as a flag in a byte\&. Depending on how many nullable columns there are, there can be one or more bytes used for this purpose\&. The
|
|
Nullpos
|
|
and
|
|
Nullbit
|
|
values, if nonempty, indicate which byte and bit contains that flag indicating whether the column is
|
|
NULL\&.
|
|
.sp
|
|
The position and number of bytes used to store
|
|
NULL
|
|
flags is shown in the line for field 1\&. This is why there are six
|
|
Field
|
|
lines for the
|
|
person
|
|
table even though it has only five columns\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Type
|
|
.sp
|
|
The data type\&. The value may contain any of the following descriptors:
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
constant
|
|
.sp
|
|
All rows have the same value\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
no endspace
|
|
.sp
|
|
Do not store endspace\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
no endspace, not_always
|
|
.sp
|
|
Do not store endspace and do not do endspace compression for all values\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
no endspace, no empty
|
|
.sp
|
|
Do not store endspace\&. Do not store empty values\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
table\-lookup
|
|
.sp
|
|
The column was converted to an
|
|
ENUM\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
zerofill(\fIN\fR)
|
|
.sp
|
|
The most significant
|
|
\fIN\fR
|
|
bytes in the value are always 0 and are not stored\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
no zeros
|
|
.sp
|
|
Do not store zeros\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
always zero
|
|
.sp
|
|
Zero values are stored using one bit\&.
|
|
.RE
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Huff tree
|
|
.sp
|
|
The number of the Huffman tree associated with the column\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Bits
|
|
.sp
|
|
The number of bits used in the Huffman tree\&.
|
|
.RE
|
|
.PP
|
|
The
|
|
Huff tree
|
|
and
|
|
Bits
|
|
fields are displayed if the table has been compressed with
|
|
\fBmyisampack\fR\&. See
|
|
\fBmyisampack\fR(1), for an example of this information\&.
|
|
.PP
|
|
Example of
|
|
\fBmyisamchk \-eiv\fR
|
|
output:
|
|
.sp
|
|
.if n \{\
|
|
.RS 4
|
|
.\}
|
|
.nf
|
|
Checking MyISAM file: person
|
|
Data records: 306688 Deleted blocks: 0
|
|
\- check file\-size
|
|
\- check record delete\-chain
|
|
No recordlinks
|
|
\- check key delete\-chain
|
|
block_size 1024:
|
|
\- check index reference
|
|
\- check data record references index: 1
|
|
Key: 1: Keyblocks used: 98% Packed: 0% Max levels: 3
|
|
\- check data record references index: 2
|
|
Key: 2: Keyblocks used: 99% Packed: 97% Max levels: 3
|
|
\- check data record references index: 3
|
|
Key: 3: Keyblocks used: 98% Packed: \-14% Max levels: 3
|
|
Total: Keyblocks used: 98% Packed: 89%
|
|
\- check records and index references
|
|
\fI*** LOTS OF ROW NUMBERS DELETED ***\fR
|
|
Records: 306688 M\&.recordlength: 25 Packed: 83%
|
|
Recordspace used: 97% Empty space: 2% Blocks/Record: 1\&.00
|
|
Record blocks: 306688 Delete blocks: 0
|
|
Record data: 7934464 Deleted data: 0
|
|
Lost space: 256512 Linkdata: 1156096
|
|
User time 43\&.08, System time 1\&.68
|
|
Maximum resident set size 0, Integral resident set size 0
|
|
Non\-physical pagefaults 0, Physical pagefaults 0, Swaps 0
|
|
Blocks in 0 out 7, Messages in 0 out 0, Signals 0
|
|
Voluntary context switches 0, Involuntary context switches 0
|
|
Maximum memory usage: 1046926 bytes (1023k)
|
|
.fi
|
|
.if n \{\
|
|
.RE
|
|
.\}
|
|
.PP
|
|
\fBmyisamchk \-eiv\fR
|
|
output includes the following information:
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Data records
|
|
.sp
|
|
The number of rows in the table\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Deleted blocks
|
|
.sp
|
|
How many deleted blocks still have reserved space\&. You can optimize your table to minimize this space\&. See
|
|
Section\ \&7.6.4, \(lqMyISAM Table Optimization\(rq\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Key
|
|
.sp
|
|
The key number\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Keyblocks used
|
|
.sp
|
|
What percentage of the keyblocks are used\&. When a table has just been reorganized with
|
|
\fBmyisamchk\fR, the values are very high (very near theoretical maximum)\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Packed
|
|
.sp
|
|
MySQL tries to pack key values that have a common suffix\&. This can only be used for indexes on
|
|
CHAR
|
|
and
|
|
VARCHAR
|
|
columns\&. For long indexed strings that have similar leftmost parts, this can significantly reduce the space used\&. In the preceding example, the second key is 40 bytes long and a 97% reduction in space is achieved\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Max levels
|
|
.sp
|
|
How deep the B\-tree for this key is\&. Large tables with long key values get high values\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Records
|
|
.sp
|
|
How many rows are in the table\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
M\&.recordlength
|
|
.sp
|
|
The average row length\&. This is the exact row length for tables with fixed\-length rows, because all rows have the same length\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Packed
|
|
.sp
|
|
MySQL strips spaces from the end of strings\&. The
|
|
Packed
|
|
value indicates the percentage of savings achieved by doing this\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Recordspace used
|
|
.sp
|
|
What percentage of the data file is used\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Empty space
|
|
.sp
|
|
What percentage of the data file is unused\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Blocks/Record
|
|
.sp
|
|
Average number of blocks per row (that is, how many links a fragmented row is composed of)\&. This is always 1\&.0 for fixed\-format tables\&. This value should stay as close to 1\&.0 as possible\&. If it gets too large, you can reorganize the table\&. See
|
|
Section\ \&7.6.4, \(lqMyISAM Table Optimization\(rq\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Recordblocks
|
|
.sp
|
|
How many blocks (links) are used\&. For fixed\-format tables, this is the same as the number of rows\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Deleteblocks
|
|
.sp
|
|
How many blocks (links) are deleted\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Recorddata
|
|
.sp
|
|
How many bytes in the data file are used\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Deleted data
|
|
.sp
|
|
How many bytes in the data file are deleted (unused)\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Lost space
|
|
.sp
|
|
If a row is updated to a shorter length, some space is lost\&. This is the sum of all such losses, in bytes\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Linkdata
|
|
.sp
|
|
When the dynamic table format is used, row fragments are linked with pointers (4 to 7 bytes each)\&.
|
|
Linkdata
|
|
is the sum of the amount of storage used by all such pointers\&.
|
|
.RE
|
|
.SH "MYISAMCHK MEMORY USAGE"
|
|
.\" memory usage: myisamchk
|
|
.PP
|
|
Memory allocation is important when you run
|
|
\fBmyisamchk\fR\&.
|
|
\fBmyisamchk\fR
|
|
uses no more memory than its memory\-related variables are set to\&. If you are going to use
|
|
\fBmyisamchk\fR
|
|
on very large tables, you should first decide how much memory you want it to use\&. The default is to use only about 3MB to perform repairs\&. By using larger values, you can get
|
|
\fBmyisamchk\fR
|
|
to operate faster\&. For example, if you have more than 512MB RAM available, you could use options such as these (in addition to any other options you might specify):
|
|
.sp
|
|
.if n \{\
|
|
.RS 4
|
|
.\}
|
|
.nf
|
|
shell> \fBmyisamchk \-\-myisam_sort_buffer_size=256M \e\fR
|
|
\fB\-\-key_buffer_size=512M \e\fR
|
|
\fB\-\-read_buffer_size=64M \e\fR
|
|
\fB\-\-write_buffer_size=64M \&.\&.\&.\fR
|
|
.fi
|
|
.if n \{\
|
|
.RE
|
|
.\}
|
|
.PP
|
|
Using
|
|
\fB\-\-myisam_sort_buffer_size=16M\fR
|
|
is probably enough for most cases\&.
|
|
.PP
|
|
Be aware that
|
|
\fBmyisamchk\fR
|
|
uses temporary files in
|
|
TMPDIR\&. If
|
|
TMPDIR
|
|
points to a memory file system, out of memory errors can easily occur\&. If this happens, run
|
|
\fBmyisamchk\fR
|
|
with the
|
|
\fB\-\-tmpdir=\fR\fB\fIpath\fR\fR
|
|
option to specify a directory located on a file system that has more space\&.
|
|
.PP
|
|
When performing repair operations,
|
|
\fBmyisamchk\fR
|
|
also needs a lot of disk space:
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Twice the size of the data file (the original file and a copy)\&. This space is not needed if you do a repair with
|
|
\fB\-\-quick\fR; in this case, only the index file is re\-created\&.
|
|
\fIThis space must be available on the same file system as the original data file\fR, as the copy is created in the same directory as the original\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
Space for the new index file that replaces the old one\&. The old index file is truncated at the start of the repair operation, so you usually ignore this space\&. This space must be available on the same file system as the original data file\&.
|
|
.RE
|
|
.sp
|
|
.RS 4
|
|
.ie n \{\
|
|
\h'-04'\(bu\h'+03'\c
|
|
.\}
|
|
.el \{\
|
|
.sp -1
|
|
.IP \(bu 2.3
|
|
.\}
|
|
When using
|
|
\fB\-\-recover\fR
|
|
or
|
|
\fB\-\-sort\-recover\fR
|
|
(but not when using
|
|
\fB\-\-safe\-recover\fR), you need space on disk for sorting\&. This space is allocated in the temporary directory (specified by
|
|
TMPDIR
|
|
or
|
|
\fB\-\-tmpdir=\fR\fB\fIpath\fR\fR)\&. The following formula yields the amount of space required:
|
|
.sp
|
|
.if n \{\
|
|
.RS 4
|
|
.\}
|
|
.nf
|
|
(\fIlargest_key\fR + \fIrow_pointer_length\fR) * \fInumber_of_rows\fR * 2
|
|
.fi
|
|
.if n \{\
|
|
.RE
|
|
.\}
|
|
.sp
|
|
You can check the length of the keys and the
|
|
\fIrow_pointer_length\fR
|
|
with
|
|
\fBmyisamchk \-dv \fR\fB\fItbl_name\fR\fR
|
|
(see
|
|
the section called \(lqOBTAINING TABLE INFORMATION WITH MYISAMCHK\(rq)\&. The
|
|
\fIrow_pointer_length\fR
|
|
and
|
|
\fInumber_of_rows\fR
|
|
values are the
|
|
Datafile pointer
|
|
and
|
|
Data records
|
|
values in the table description\&. To determine the
|
|
\fIlargest_key\fR
|
|
value, check the
|
|
Key
|
|
lines in the table description\&. The
|
|
Len
|
|
column indicates the number of bytes for each key part\&. For a multiple\-column index, the key size is the sum of the
|
|
Len
|
|
values for all key parts\&.
|
|
.RE
|
|
.PP
|
|
If you have a problem with disk space during repair, you can try
|
|
\fB\-\-safe\-recover\fR
|
|
instead of
|
|
\fB\-\-recover\fR\&.
|
|
.SH "COPYRIGHT"
|
|
.br
|
|
.PP
|
|
Copyright \(co 1997, 2013, Oracle and/or its affiliates. All rights reserved.
|
|
.PP
|
|
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.
|
|
.PP
|
|
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.
|
|
.PP
|
|
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/.
|
|
.sp
|
|
.SH "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/.
|
|
.SH AUTHOR
|
|
Oracle Corporation (http://dev.mysql.com/).
|