13.7.7.17. Integration with MySQL PERFORMANCE_SCHEMA

Starting with InnoDB 1.1 with MySQL 5.5, you can profile certain internal InnoDB operations using the MySQL Performance Schema feature. This type of tuning is primarily for expert users, those who push the limits of MySQL performance, read the MySQL source code, and evaluate optimization strategies to overcome performance bottlenecks. DBAs can also use this feature for capacity planning, to see whether their typical workload encounters any performance bottlenecks with a particular combination of CPU, RAM, and disk storage; and if so, to judge whether performance can be improved by increasing the capacity of some part of the system.

To use this feature to examine InnoDB performance:

  • You must be running MySQL 5.5 or higher. You must build the database server from source, enabling the Performance Schema feature by building with the --with-perfschema option. Since the Performance Schema feature introduces some performance overhead, you should use it on a test or development system rather than on a production system.

  • You must be running InnoDB 1.1 or higher.

  • You must be generally familiar with how to use the Performance Schema feature, for example to query tables in the performance_schema database.

  • Examine the following kinds of InnoDB objects by querying the appropriate performance_schema tables. The items associated with InnoDB all contain the substring innodb in the NAME column.

    For the definitions of the *_INSTANCES tables, see Section 21.7.5, “Performance Schema Instance Tables”. For the definitions of the *_SUMMARY_* tables, see Section 21.7.4, “Performance Schema Summary Tables”. For the definition of the PROCESSLIST table, see Section 21.7.6, “Performance Schema Miscellaneous Tables”. For the definition of the *_CURRENT_* tables, see Section 21.7.2, “Performance Schema Events (Current) Table”. For the definition of the *_HISTORY_* tables, see Section 21.7.3, “Performance Schema History Tables”.

    • Mutexes in the mutex_instances table. (Mutexes and RW-locks related to the InnoDB buffer pool are not included in this coverage; the same applies to the output of the SHOW ENGINE INNODB MUTEX command.)

    • RW-locks in the rwlock_instances table.

    • RW-locks in the rwlock_instances table.

    • File I/O operations in the file_instances, file_summary_by_event_name, and file_summary_by_instance tables.

    • Threads in the PROCESSLIST table.

  • During performance testing, examine the performance data in the events_waits_current and events_waits_history_long tables. If you are interested especially in InnoDB-related objects, use the clause where name like "%innodb%" to see just those entries; otherwise, examine the performance statistics for the overall MySQL server.

  • You must be running MySQL 5.5, with the Performance Schema enabled by building with the --with-perfschema build option.

For more information about the MySQL Performance Schema, see Chapter 21, MySQL Performance Schema.

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