MySQL 8.0 Release Notes
MySQL 8.0 Source Code Documentation
This section describes how to rebuild or repair tables or indexes, which may be necessitated by:
Changes to how MySQL handles data types or character sets. For example, an error in a collation might have been corrected, necessitating a table rebuild to update the indexes for character columns that use the collation.
Required table repairs or upgrades reported by
CHECK TABLE, mysqlcheck, or mysql_upgrade.
Methods for rebuilding a table include:
If you are rebuilding tables because a different version of MySQL will not handle them after a binary (in-place) upgrade or downgrade, you must use the dump-and-reload method. Dump the tables before upgrading or downgrading using your original version of MySQL. Then reload the tables after upgrading or downgrading.
If you use the dump-and-reload method of rebuilding tables only for the purpose of rebuilding indexes, you can perform the dump either before or after upgrading or downgrading. Reloading still must be done afterward.
If you need to rebuild an InnoDB table
because a CHECK TABLE operation
indicates that a table upgrade is required, use
mysqldump to create a dump file and
mysql to reload the file. If the
CHECK TABLE operation indicates
that there is a corruption or causes InnoDB
to fail, refer to Section 15.20.2, “Forcing InnoDB Recovery” for
information about using the
innodb_force_recovery option to
restart InnoDB. To understand the type of
problem that CHECK TABLE may be
encountering, refer to the InnoDB notes in
Section 13.7.3.2, “CHECK TABLE Syntax”.
To rebuild a table by dumping and reloading it, use mysqldump to create a dump file and mysql to reload the file:
mysqldump db_name t1 > dump.sql
mysql db_name < dump.sqlTo rebuild all the tables in a single database, specify the database name without any following table name:
mysqldump db_name > dump.sql
mysql db_name < dump.sql
To rebuild all tables in all databases, use the
--all-databases option:
mysqldump --all-databases > dump.sql
mysql < dump.sql
To rebuild a table with ALTER
TABLE, use a “null” alteration; that is,
an ALTER TABLE statement that
“changes” the table to use the storage engine that
it already has. For example, if t1 is an
InnoDB table, use this statement:
ALTER TABLE t1 ENGINE = InnoDB;
If you are not sure which storage engine to specify in the
ALTER TABLE statement, use
SHOW CREATE TABLE to display the
table definition.
The REPAIR TABLE method is only
applicable to MyISAM,
ARCHIVE, and CSV tables.
You can use REPAIR TABLE if the
table checking operation indicates that there is a corruption or
that an upgrade is required. For example, to repair a
MyISAM table, use this statement:
REPAIR TABLE t1;
mysqlcheck --repair provides command-line
access to the REPAIR TABLE
statement. This can be a more convenient means of repairing
tables because you can use the
--databases or
--all-databases option to
repair all tables in specific databases or all databases,
respectively:
mysqlcheck --repair --databases db_name ...
mysqlcheck --repair --all-databases