Performance Schema Instance Tables The instrument name. Thread instruments begin with  thread  (for example,  thread/sql/ parser_service  or  thread/performance_schema/setup ). 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. 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. The instrument properties. This column uses the  SET  data type, so multiple flags from the following list can be set per instrument: The instrument volatility. This column has the same meaning as in the  setup_instruments  table. See Section 27.12.2.3, “The setup_instruments Table” . A string describing the instrument purpose. The value is  NULL  if no description is available. The  setup_threads  table has these indexes: TRUNCATE TABLE  is not permitted for the  setup_threads  table. This table was removed in MySQL 8.0.4. Instance tables document what types of objects are instrumented. They provide event names and explanatory notes or status information: • ENABLED • HISTORY • PROPERTIES • 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 • DOCUMENTATION 27.12.2.6 The setup_timers Table 27.12.3 Performance Schema Instance Tables 4952 •Primary key on ( NAME )