The setup_actors table contains information that determines whether to enable monitoring for new foreground server threads; that is, threads associated with client connections. This table has a maximum size of 100 rows by default. The size may be changed by modifying the performance_schema_setup_actors_size system variable at server startup.

The setup_actors table has these columns:

For each new foreground thread, the Performance Schema matches the user and host for the the thread against the rows of the setup_actors table. Based on whether any row matches, the INSTRUMENTED column of the threads table row for the thread is set to YES or NO. This enables instrumenting to be applied selectively per host, user, or combination of host and user.

The initial contents of the setup_actors table match any user and host combination, so monitoring for all foreground threads is enabled by default:

mysql> SELECT * FROM setup_actors;
+------+------+------+
| HOST | USER | ROLE |
+------+------+------+
| %    | %    | %    |
+------+------+------+

Modifications to the setup_actors table do not affect existing threads.

For more information about the role of the setup_actors table in event monitoring, see Section 21.2.3.2.1, “Event Pre-Filtering”.