All checked and repaired tables are marked with the current MySQL version number. This ensures that next time you run mysql_upgrade with the same version of the server, it can tell whether there is any need to check or repair the table again.
mysql_upgrade also saves the MySQL version number in a file named mysql_upgrade.info in the data directory. This is used to quickly check if all tables have been checked for this release so that table-checking can be skipped. To ignore this file, use the --force option.
To check and repair tables and to upgrade the system tables, mysql_upgrade executes the following commands:
mysqlcheck --check-upgrade --all-databases --auto-repair mysql_fix_privilege_tables
mysql_upgrade supersedes the older mysql_fix_privilege_tables script. In MySQL 5.0.19, mysql_upgrade was added as a shell script and worked only for Unix systems. As of MySQL 5.0.23, mysql_upgrade is an executable binary and is available on all systems. On systems older than those supporting mysql_upgrade, you can execute the mysqlcheck command manually, and then upgrade your system tables as described in mysql_fix_privilege_tables(1).
For details about what is checked, see the description of the FOR UPGRADE option of the CHECK TABLE statement (see Section 5.2.3, lqCHECK TABLE Syntaxrq).
To use mysql_upgrade, make sure that the server is running, and then invoke it like this:
shell> mysql_upgrade [options]
mysql_upgrade reads options from the command line and fromm the [mysqld] and [mysql_upgrade] groups in option files. It supports the following options:
Display a short help message and exit.
The path to the MySQL installation directory.
The path to the data directory.
Force execution of mysqlcheck even if mysql_upgrade has already been executed for the current version of MySQL. (In other words, this option causes the mysql_upgrade.info file to be ignored.)
The MySQL username to use when connecting to the server. The default username is root.
Verbose mode. Print more information about what the program does.
Other options are passed to mysqlcheck and to mysql_fix_privilege_tables. For example, it might be necessary to specify the --password[=password] option.