Event Pre-opracowanie

Event Pre-Filtering
Pre-filtering is done by the Performance Schema and has a global effect that applies to all users. Prefiltering
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:
• The setup_instruments table 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.
• The setup_objects table determines whether particular objects are monitored. Currently, the
Performance Schema uses it to control monitoring of table objects.
• The threads table indicates whether monitoring is enabled for each server thread.
• The setup_actors table 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.
The setup_consumers table also implicitly affects event production. If a given event will not be
sent to any destination (that is, will not be consumed), the Performance Schema does not produce it.
Modifications to any of these tables affect monitoring immediately, with the exception of
setup_actors. Modifications to setup_actors affect only foreground threads created thereafter.
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
as well to clear aggregate information for previously collected events. Except for
events_statements_summary_by_digest, the effect of TRUNCATE TABLE for summary tables is
to reset the summary columns to 0 or NULL, not to remove rows.
The following sections describe how to use specific tables to control how the Performance Schema
performs pre-filtering.
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