21.2.3. Performance Schema Runtime Configuration

Performance Schema setup tables contain information about monitoring configuration:

mysql> SELECT TABLE_NAME FROM
        INFORMATION_SCHEMA.TABLES    -> WHERE TABLE_SCHEMA =
        'performance_schema'    -> AND TABLE_NAME LIKE
        'setup%';+-------------------+| TABLE_NAME        |+-------------------+| setup_actors      || setup_consumers   || setup_instruments || setup_objects     || setup_timers      |+-------------------+

You can examine the contents of these tables to obtain information about Performance Schema monitoring characteristics. If you have the UPDATE privilege, you can change Performance Schema operation by modifying setup tables to affect how monitoring occurs. For additional details about these tables, see Section 21.9.1, "Performance Schema Setup Tables".

To see which event timers are selected, query the setup_timers tables:

mysql> SELECT * FROM setup_timers;+-----------+-------------+| NAME      | TIMER_NAME  |+-----------+-------------+| idle      | MICROSECOND || wait      | CYCLE       || stage     | NANOSECOND  || statement | NANOSECOND  |+-----------+-------------+

The NAME value indicates the type of instrument to which the timer applies, and TIMER_NAME indicates which timer applies to those instruments. The timer applies to instruments where their name begins with a component matching the NAME value.

To change the timer, update the NAME value. For example, to use the NANOSECOND timer for the wait timer:

mysql> UPDATE setup_timers SET TIMER_NAME =
        'NANOSECOND'    -> WHERE NAME = 'wait';mysql> SELECT * FROM setup_timers;+-----------+-------------+| NAME      | TIMER_NAME  |+-----------+-------------+| idle      | MICROSECOND || wait      | NANOSECOND  || stage     | NANOSECOND  || statement | NANOSECOND  |+-----------+-------------+

For discussion of timers, see Section 21.2.3.1, "Performance Schema Event Timing".

The setup_instruments and setup_consumers tables list the instruments for which events can be collected and the types of consumers for which event information actually is collected, respectively. Other setup tables enable further modification of the monitoring configuration. Section 21.2.3.2, "Performance Schema Event Filtering", discusses how you can modify these tables to affect event collection.

If there are Performance Schema configuration changes that must be made at runtime using SQL statements and you would like to these changes take effect each time the server starts, put the statements in a file and start the server with the --init-file=file_name option. This strategy can also be useful if you have multiple monitoring configurations, each tailored to produce a different kind of monitoring, such as casual server health monitoring, incident investigation, application behavior troubleshooting, and so forth. Put the statements for each monitoring configuration into their own file and specify the appropriate file as the --init-file argument when you start the server.