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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. 

## 27.16 Performance Schema Status Variables 

The Performance Schema implements several status variables that provide information about instrumentation that could not be loaded or created due to memory constraints: 

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: 

• Performance_schema_accounts_lost 

The number of times a row could not be added to the accounts  table because it was full. 

• Performance_schema_cond_classes_lost 

How many condition instruments could not be loaded. 

• Performance_schema_cond_instances_lost 

How many condition instrument instances could not be created. 

• Performance_schema_digest_lost 

