MySQL Performance Schema is a feature for monitoring MySQL Server execution at a low level.Performance Schema is intended to provide access to useful information about server execution while having minimal impact on server performance
Performance Schema has these characteristics:
1.Performance Schema provides a way to inspect internal execution of the server at runtime.
2.Performance Schema monitors server events.
3.Performance Schema events are distinct from events written to the server's binary log (which describe data modifications) and Event Scheduler events (which are a type of stored program).
4.The PERFORMANCE_SCHEMA storage engine collects event data using “instrumentation points” in server source code.
5.Performance Schema configuration can be modified dynamically by updating tables in the performance_schema database via SQL statements. Configuration changes affect data collection immediately.
6.Tables in the performance_schema database are views or temporary tables that use no persistent on-disk storage.

If Performance Schema is available, the output will mention several variables with names that begin with performance_schema: