As noted in Section 8.6, “Controlling Optimizer Statistics Estimation”, the InnoDB storage engine allows you to control the way in which InnoDB gathers information about the number of distinct values in an index key. A related parameter, innodb_stats_on_metadata, has existed since MySQL release 5.1.17 to control whether or not InnoDB performs statistics gathering when metadata statements are executed. See the MySQL manual on InnoDB Startup Options and System Variables for details.

Beginning with release 1.0.2 of the InnoDB storage engine, it is possible to change the setting of innodb_stats_on_metadata dynamically at runtime with the command SET GLOBAL innodb_stats_on_metadata=mode, where mode is either ON or OFF (or 1 or 0). Changing this setting requires the SUPER privilege and immediately affects the operation of all connections.