10.2.5 The setup_threads Table

The setup_threads table lists instrumented thread classes. It exposes thread class names and attributes:

mysql> SELECT * FROM performance_schema.setup_threads\G
*************************** 1. row ***************************
         NAME: thread/performance_schema/setup
      ENABLED: YES
      HISTORY: YES
   PROPERTIES: singleton
   VOLATILITY: 0
DOCUMENTATION: NULL
...
*************************** 4. row ***************************
         NAME: thread/sql/main
      ENABLED: YES
      HISTORY: YES
   PROPERTIES: singleton
   VOLATILITY: 0
DOCUMENTATION: NULL
*************************** 5. row ***************************
         NAME: thread/sql/one_connection
      ENABLED: YES
      HISTORY: YES
   PROPERTIES: user
   VOLATILITY: 0
DOCUMENTATION: NULL
...
*************************** 10. row ***************************
         NAME: thread/sql/event_scheduler
      ENABLED: YES
      HISTORY: YES
   PROPERTIES: singleton
   VOLATILITY: 0
DOCUMENTATION: NULL

The setup_threads table has these columns:

• NAME

  The instrument name. Thread instruments begin with thread (for example, thread/sql/parser_service or thread/performance_schema/setup).

• ENABLED

  Whether the instrument is enabled. The value is YES or NO. This column can be modified, although setting ENABLED has no effect for threads that are already running.

  For background threads, setting the ENABLED value controls whether INSTRUMENTED is set to YES or NO for threads that are subsequently created for this instrument and listed in the threads table. For foreground threads, this column has no effect; the setup_actors table takes precedence.

• HISTORY

  Whether to log historical events for the instrument. The value is YES or NO. This column can be modified, although setting HISTORY has no effect for threads that are already running.

  For background threads, setting the HISTORY value controls whether HISTORY is set to YES or NO for threads that are subsequently created for this instrument and listed in the threads table. For foreground threads, this column has no effect; the setup_actors table takes precedence.

• PROPERTIES

  The instrument properties. This column uses the SET data type, so multiple flags from the following list can be set per instrument:

  • singleton: The instrument has a single instance. For example, there is only one thread for the thread/sql/main instrument.

  • user: The instrument is directly related to user workload (as opposed to system workload). For example, threads such as thread/sql/one_connection executing a user session have the user property to differentiate them from system threads.

• VOLATILITY

  The instrument volatility. This column has the same meaning as in the setup_instruments table. See Section 10.2.3, “The setup_instruments Table”.

• DOCUMENTATION

  A string describing the instrument purpose. The value is NULL if no description is available.

The setup_threads table has these indexes:

• Primary key on (NAME)

TRUNCATE TABLE is not permitted for the setup_threads table.