Performance Schema Status Variable Tables The session variable tables ( session_status ,  status_by_thread ) contain information only for active sessions, not terminated sessions. The Performance Schema collects statistics for global status variables only for threads for which the INSTRUMENTED  value is  YES  in the  threads  table. Statistics for session status variables are always collected, regardless of the  INSTRUMENTED  value. The Performance Schema does not collect statistics for  Com_ xxx  status variables in the status variable tables. To obtain global and per-session statement execution counts, use the  events_statements_summary_global_by_event_name  and events_statements_summary_by_thread_by_event_name  tables, respectively. For example: SELECT EVENT_NAME, COUNT_STAR FROM performance_schema.events_statements_summary_global_by_event_name WHERE EVENT_NAME LIKE ’statement/sql/%’; The  global_status  and  session_status  tables have these columns: The status variable name. The status variable value. For  global_status , this column contains the global value. For session_status , this column contains the variable value for the current session. • VARIABLE_NAME • VARIABLE_VALUE • THREAD_ID •Primary key on ( VARIABLE_NAME ) • VARIABLE_NAME • VARIABLE_VALUE •Primary key on ( THREAD_ID ,  VARIABLE_NAME ) The  global_status  and  session_status  tables have these indexes: The  status_by_thread  table contains the status of each active thread. It has these columns: The thread identifier of the session in which the status variable is defined. The status variable name. The session variable value for the session named by the  THREAD_ID  column. The  status_by_thread  table has these indexes: The  status_by_thread  table contains status variable information only about foreground threads. If the performance_schema_max_thread_instances  system variable is not autoscaled (signified by a value of  − 1) and the maximum permitted number of instrumented thread objects is not greater than the number of background threads, the table is empty. The Performance Schema supports  TRUNCATE TABLE  for status variable tables as follows: • global_status : Resets thread, account, host, and user status. Resets global status variables except those that the server never resets. 5036