Pre-filtering is done by the Performance Schema and has a global effect that applies to all users. Pre-filtering can be applied to either the producer or consumer stage of event processing:
To configure pre-filtering at the producer stage, several tables can be used:
setup_instruments
indicates which instruments are available. An instrument disabled in this table produces no events regardless of the contents of the other production-related setup tables. An instrument enabled in this table is permitted to produce events, subject to the contents of the other tables.setup_objects
controls whether the Performance Schema monitors particular table and stored program objects.threads
indicates whether monitoring is enabled for each server thread.setup_actors
determines the initial monitoring state for new foreground threads.
To configure pre-filtering at the consumer stage, modify the
setup_consumers
table. This determines the destinations to which events are sent.setup_consumers
also implicitly affects event production. If a given event is not sent to any destination (that is, it is never consumed), the Performance Schema does not produce it.
Modifications to any of these tables affect monitoring
immediately, with the exception that modifications to the
setup_actors
table affect only
foreground threads created subsequent to the modification, not
existing threads.
When you change the monitoring configuration, the Performance
Schema does not flush the history tables. Events already
collected remain in the current-events and history tables until
displaced by newer events. If you disable instruments, you might
need to wait a while before events for them are displaced by
newer events of interest. Alternatively, use
TRUNCATE TABLE
to empty the
history tables.
After making instrumentation changes, you might want to truncate
the summary tables. Generally, the effect is to reset the
summary columns to 0 or NULL
, not to remove
rows. This enables you to clear collected values and restart
aggregation. That might be useful, for example, after you have
made a runtime configuration change. Exceptions to this
truncation behavior are noted in individual summary table
sections.
The following sections describe how to use specific tables to control Performance Schema pre-filtering.