Performance Schema Status Variables Type Integer Default Value -1  (signifies autoscaling; do not assign this literal value) Minimum Value -1  (signifies autoscaling; do not assign this literal value) Maximum Value 1048576 The number of rows in the  users  table. If this variable is 0, the Performance Schema does not maintain connection statistics in the  users  table or status variable information in the  status_by_user  table. The Performance Schema implements several status variables that provide information about instrumentation that could not be loaded or created due to memory constraints: 27.16 Performance Schema Status Variables mysql>  SHOW STATUS LIKE ’perf%’; +-------------------------------------------+-------+ | Variable_name | Value | +-------------------------------------------+-------+ | Performance_schema_accounts_lost | 0 | | Performance_schema_cond_classes_lost | 0 | | Performance_schema_cond_instances_lost | 0 | | Performance_schema_file_classes_lost | 0 | | Performance_schema_file_handles_lost | 0 | | Performance_schema_file_instances_lost | 0 | | Performance_schema_hosts_lost | 0 | | Performance_schema_locker_lost | 0 | | Performance_schema_mutex_classes_lost | 0 | | Performance_schema_mutex_instances_lost | 0 | | Performance_schema_rwlock_classes_lost | 0 | | Performance_schema_rwlock_instances_lost | 0 | | Performance_schema_socket_classes_lost | 0 | | Performance_schema_socket_instances_lost | 0 | | Performance_schema_stage_classes_lost | 0 | | Performance_schema_statement_classes_lost | 0 | | Performance_schema_table_handles_lost | 0 | | Performance_schema_table_instances_lost | 0 | | Performance_schema_thread_classes_lost | 0 | | Performance_schema_thread_instances_lost | 0 | | Performance_schema_users_lost | 0 | +-------------------------------------------+-------+ For information on using these variables to check Performance Schema status, see Section 27.7, “Performance Schema Status Monitoring” . Performance Schema status variables have the following meanings: How many condition instruments could not be loaded. The number of times a row could not be added to the  accounts  table because it was full. How many condition instrument instances could not be created. 5119 • Performance_schema_digest_lost • Performance_schema_cond_instances_lost • Performance_schema_cond_classes_lost • Performance_schema_accounts_lost