Before starting to database performance tuning activities, Database Administrator requires different types of statistics like wait events, connection time, instance information, lock tables.

MySQL 5.5 introduced a PERFORMANCE_SCHEMA storage engine to monitor the performance of data and different types of server events.
One performance_schema database is created under the PERFORMANCE_SCHEMA storage engine.

An INFORMATION_SCHEMA focuses on METADATA information, but PERFORMANCE_SCHEMA primary focuses on MySQL Database Performance related Data.

The Performance Schema is also collecting different types of MySQL Server event with the related time information.
It stores all collected information in the table so that we can easily access it.

The Performance Schema events are specific to an instance of MySQL Server and changes are not written to the binary log.

We can set enable or disable PERFORMANCE_SCHEMA storage engine. Once it enables, it collects and monitors the different performance related event stats.

The main advantage of Performance Schema is, it never changes the server behaviour and never disturb to Query Planner for making a Query Execution Plan.

The execution of server proceeds normally even if the Performance Schema fails internally.

Please visit the next article about, How to configure Performance Schema and basic usage of it.