Performance Schema Queries | wait/io/file/innodb/innodb_arch_file | YES | YES | | wait/io/file/innodb/innodb_clone_file | YES | YES | +-------------------------------------------------+---------+-------+ An exhaustive description of precisely what is instrumented is not given in this documentation, for several reasons: •What is instrumented is the server code. Changes to this code occur often, which also affects the set of instruments. •It is not practical to list all the instruments because there are hundreds of them. •As described earlier, it is possible to find out by querying the  setup_instruments  table. This information is always up to date for your version of MySQL, also includes instrumentation for instrumented plugins you might have installed that are not part of the core server, and can be used by automated tools. 27.5 Performance Schema Queries Pre-filtering limits which event information is collected and is independent of any particular user. By contrast, post-filtering is performed by individual users through the use of queries with appropriate  WHERE clauses that restrict what event information to select from the events available after pre-filtering has been applied. In Section 27.4.3, “Event Pre-Filtering” , an example showed how to pre-filter for file instruments. If the event tables contain both file and nonfile information, post-filtering is another way to see information only for file events. Add a  WHERE  clause to queries to restrict event selection appropriately: mysql>  SELECT THREAD_ID, NUMBER_OF_BYTES FROM performance_schema.events_waits_history WHERE EVENT_NAME LIKE ’wait/io/file/%’ AND NUMBER_OF_BYTES IS NOT NULL; +-----------+-----------------+ | THREAD_ID | NUMBER_OF_BYTES | +-----------+-----------------+ | 11 | 66 | | 11 | 47 | | 11 | 139 | | 5 | 24 | | 5 | 834 | +-----------+-----------------+ Most Performance Schema tables have indexes, which gives the optimizer access to execution plans other than full table scans. These indexes also improve performance for related objects, such as  sys  schema views that use those tables. For more information, see Section 8.2.4, “Optimizing Performance Schema Queries” . 27.6 Performance Schema Instrument Naming Conventions An instrument name consists of a sequence of elements separated by  ’/’  characters. Example names: wait/io/file/myisam/log wait/io/file/mysys/charset wait/lock/table/sql/handler wait/synch/cond/mysys/COND_alarm wait/synch/cond/sql/BINLOG::update_cond wait/synch/mutex/mysys/BITMAP_mutex wait/synch/mutex/sql/LOCK_delete wait/synch/rwlock/sql/Query_cache_query::lock stage/sql/closing tables 4924