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MySQL 8.0 Reference Manual  /  ...  /  Performance Schema Wait Event Tables

25.11.4 Performance Schema Wait Event Tables

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; see Section 25.11.16.1, “Wait Event Summary Tables”.

Wait Event Configuration

To control collection of wait events, set the state of the relevant instruments and consumers:

  • The setup_instruments table contains instruments with names that begin with wait. Use these instruments to enable or disable collection of wait events.

  • The setup_consumers table contains consumer values with names corresponding to the current and recent wait event table names. Use these consumers to filter collection of wait events.

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 '%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 your my.cnf file:

  • Enable:

    [mysqld]
    performance-schema-instrument='wait/%=ON'
    performance-schema-consumer-events-waits-current=ON
    performance-schema-consumer-events-waits-history=ON
    performance-schema-consumer-events-waits-history-long=ON
  • Disable:

    [mysqld]
    performance-schema-instrument='wait/%=OFF'
    performance-schema-consumer-events-waits-current=OFF
    performance-schema-consumer-events-waits-history=OFF
    performance-schema-consumer-events-waits-history-long=OFF

To control wait event collection at runtime, update the setup_instruments and setup_consumers tables:

  • Enable:

    UPDATE performance_schema.setup_instruments
    SET ENABLED = 'YES', TIMED = 'YES'
    WHERE NAME = 'wait/%';
    
    UPDATE performance_schema.setup_consumers
    SET ENABLED = 'YES'
    WHERE NAME LIKE '%waits%';
  • Disable:

    UPDATE performance_schema.setup_instruments
    SET ENABLED = 'NO', TIMED = 'NO'
    WHERE NAME = 'wait/%';
    
    UPDATE performance_schema.setup_consumers
    SET ENABLED = 'NO'
    WHERE NAME LIKE '%waits%';

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, see Section 25.3, “Performance Schema Startup Configuration”, and Section 25.4, “Performance Schema Runtime Configuration”.


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