Performance Schema Setup Tables Whether the instrument is enabled. The value is  YES  or  NO . A disabled instrument produces no events. This column can be modified, although setting  ENABLED  has no effect for instruments that have already been created. Whether the instrument is timed. The value is  YES ,  NO , or  NULL . This column can be modified, although setting  TIMED  has no effect for instruments that have already been created. A  TIMED  value of  NULL  indicates that the instrument does not support timing. For example, memory operations are not timed, so their  TIMED  column is  NULL . Setting  TIMED  to  NULL  for an instrument that supports timing has no effect, as does setting  TIMED  to non- NULL  for an instrument that does not support timing. If an enabled instrument is not timed, the instrument code is enabled, but the timer is not. Events produced by the instrument have  NULL  for the  TIMER_START ,  TIMER_END , and  TIMER_WAIT  timer values. This in turn causes those values to be ignored when calculating the sum, minimum, maximum, and average time values in summary tables. The instrument properties. This column uses the  SET  data type, so multiple flags from the following list can be set per instrument: • TIMED • PROPERTIES • global_statistics : The instrument produces only global summaries. Summaries for finer levels are unavailable, such as per thread, account, user, or host. For example, most memory instruments produce only global summaries. • mutable : The instrument can “mutate”  into a more specific one. This property applies only to statement instruments. • progress : The instrument is capable of reporting progress data. This property applies only to stage instruments. • singleton : The instrument has a single instance. For example, most global mutex locks in the server are singletons, so the corresponding instruments are as well. • user : The instrument is directly related to user workload (as opposed to system workload). One such instrument is  wait/io/socket/sql/client_connection . • VOLATILITY The instrument volatility. Volatility values range from low to high. The values correspond to the PSI_VOLATILITY_ xxx  constants defined in the  mysql/psi/psi_base.h  header file: The  VOLATILITY  column is purely informational, to provide users (and the Performance Schema code) some hint about the instrument runtime behavior. #define PSI_VOLATILITY_UNKNOWN 0 #define PSI_VOLATILITY_PERMANENT 1 #define PSI_VOLATILITY_PROVISIONING 2 #define PSI_VOLATILITY_DDL 3 #define PSI_VOLATILITY_CACHE 4 #define PSI_VOLATILITY_SESSION 5 #define PSI_VOLATILITY_TRANSACTION 6 #define PSI_VOLATILITY_QUERY 7 #define PSI_VOLATILITY_INTRA_QUERY 8 4948