mysql_upgrade should be executed each time you upgrade MySQL. It checks all tables in all databases for incompatibilities with the current version of MySQL Server. If a table is found to have a possible incompatibility, it is checked. If any problems are found, the table is repaired. mysql_upgrade also upgrades the system tables so that you can take advantage of new privileges or capabilities that might have been added.

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 5.1.7, mysql_upgrade was added as a shell script and worked only for Unix systems. As of MySQL 5.1.10, 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 Section 4.4.4, “mysql_fix_privilege_tables — Upgrade MySQL System Tables”.

If you install MySQL from RPM packages on Linux, you must install the server and client RPMs. mysql_upgrade is included in the server RPM but requires the client RPM because the latter includes mysqlcheck. (See Section 2.4, “Installing MySQL from RPM Packages on Linux”.)

For details about what is checked, see the description of the FOR UPGRADE option of the CHECK TABLE statement (see Section 12.5.2.2, “CHECK TABLE Syntax”).

To use mysql_upgrade, make sure that the server is running, and then invoke it like this:

shell> mysql_upgrade [options]

After running mysql_upgrade, stop the server and restart it so that it uses any changes that were made to the system tables.

mysql_upgrade reads options from the command line and from the [mysql_upgrade] group in option files. It supports the options in the following list. Other options are passed to mysqlcheck and to mysql_fix_privilege_tables. For example, it might be necessary to specify the --password[=password] option.