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The Performance Schema instruments waits, which are events that take time. Within the event hierarchy, wait events nest within stage events, which nest within statement events, which nest within transaction events.

These tables store wait events:

The following sections describe the wait event tables. There are also summary tables that aggregate information about wait events; seeSection 29.12.20.1, “Wait Event Summary Tables”.

For more information about the relationship between the three wait event tables, seeSection 29.9, “Performance Schema Tables for Current and Historical Events”.

Configuring Wait Event Collection

To control whether to collect wait events, set the state of the relevant instruments and consumers:

Some wait instruments are enabled by default; others are disabled. For example:

mysql> SELECT NAME, ENABLED, TIMED       FROM performance_schema.setup_instruments       WHERE NAME LIKE 'wait/io/file/innodb%';+-------------------------------------------------+---------+-------+| NAME                                            | ENABLED | TIMED |+-------------------------------------------------+---------+-------+| wait/io/file/innodb/innodb_tablespace_open_file | YES     | YES   || wait/io/file/innodb/innodb_data_file            | YES     | YES   || wait/io/file/innodb/innodb_log_file             | YES     | YES   || wait/io/file/innodb/innodb_temp_file            | YES     | YES   || wait/io/file/innodb/innodb_arch_file            | YES     | YES   || wait/io/file/innodb/innodb_clone_file           | YES     | YES   |+-------------------------------------------------+---------+-------+mysql> SELECT NAME, ENABLED, TIMED       FROM performance_schema.setup_instruments       WHERE NAME LIKE 'wait/io/socket/%';+----------------------------------------+---------+-------+| NAME                                   | ENABLED | TIMED |+----------------------------------------+---------+-------+| wait/io/socket/sql/server_tcpip_socket | NO      | NO    || wait/io/socket/sql/server_unix_socket  | NO      | NO    || wait/io/socket/sql/client_connection   | NO      | NO    |+----------------------------------------+---------+-------+

The wait consumers are disabled by default:

mysql> SELECT *       FROM performance_schema.setup_consumers       WHERE NAME LIKE 'events_waits%';+---------------------------+---------+| NAME                      | ENABLED |+---------------------------+---------+| events_waits_current      | NO      || events_waits_history      | NO      || events_waits_history_long | NO      |+---------------------------+---------+

To control wait event collection at server startup, use lines like these in yourmy.cnf file:

To control wait event collection at runtime, update thesetup_instruments andsetup_consumers tables:

To collect only specific wait events, enable only the corresponding wait instruments. To collect wait events only for specific wait event tables, enable the wait instruments but only the wait consumers corresponding to the desired tables.

For additional information about configuring event collection, seeSection 29.3, “Performance Schema Startup Configuration”, andSection 29.4, “Performance Schema Runtime Configuration”.