Description:
MySQL 5.6 provides several counters on data lost by P_S. E.g.
root@myhost [performance_schema]> show global status like 'performance_schema%';
+-----------------------------------------------+---------+
| Variable_name | Value |
+-----------------------------------------------+---------+
| Performance_schema_accounts_lost | 2232186 |
| Performance_schema_cond_classes_lost | 0 |
| Performance_schema_cond_instances_lost | 0 |
| Performance_schema_digest_lost | 0 |
| Performance_schema_file_classes_lost | 0 |
| Performance_schema_file_handles_lost | 0 |
| Performance_schema_file_instances_lost | 0 |
| Performance_schema_hosts_lost | 476719 |
| 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_session_connect_attrs_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 |
+-----------------------------------------------+---------+
23 rows in set (0.00 sec)
These values should be at 0. If they're not it indicates a P_S sizing "misconfiguration" that's probably not intended.
How to repeat:
See above.
Suggested fix:
Make a graph in MEM which reveals these "lost" events so we can see if any of them is > 0 and then identify which configuration adjustment may be needed.
for one of these the host_cache_size is dynamic so easy to fix.
Advisors for this might also be useful, especially if a good pointer to which values would need to be adjusted where. The graphs are good as even if the advisors are not enabled you can "see" any issues immediately.
