5.9.4. Table Maintenance and Crash Recovery
This section discusses how to use myisamchk
to check or repair MyISAM tables (tables that
have .MYD and .MYI
files for storing data and indexes). For general
myisamchk background, see
Section 8.2, “myisamchk — MyISAM Table-Maintenance Utility”.
You can use myisamchk to get information
about your database tables or to check, repair, or optimize
them. The following sections describe how to perform these
operations and how to set up a table maintenance schedule.
Even though table repair with myisamchk is
quite secure, it is always a good idea to make a backup
before doing a repair or any maintenance
operation that could make a lot of changes to a table
myisamchk operations that affect indexes can
cause FULLTEXT indexes to be rebuilt with
full-text parameters that are incompatible with the values used
by the MySQL server. To avoid this problem, follow the
guidelines in Section 8.2.1, “myisamchk General Options”.
In many cases, you may find it simpler to do
MyISAM table maintenance using the SQL
statements that perform operations that
myisamchk can do:
To check or repair MyISAM tables, use
CHECK TABLE or REPAIR
TABLE.
To optimize MyISAM tables, use
OPTIMIZE TABLE.
To analyze MyISAM tables, use
ANALYZE TABLE.
These statements can be used directly or by means of the
mysqlcheck client program. One advantage of
these statements over myisamchk is that the
server does all the work. With myisamchk, you
must make sure that the server does not use the tables at the
same time so that there is no unwanted interaction between
myisamchk and the server. See
Section 13.5.2.1, “ANALYZE TABLE Syntax”, Section 13.5.2.3, “CHECK TABLE Syntax”,
Section 13.5.2.5, “OPTIMIZE TABLE Syntax”, and
Section 13.5.2.6, “REPAIR TABLE Syntax”.
