Mysql Event Scheduler

event由特殊的event_scheduler线程来执行，
通过以下方式， 显示运行的线程信息
SELECT * FROM INFORMATION_SCHEMA.PROCESSLIST;
或
SHOW FULL PROCESSLIST;/SHOW FULL PROCESSLIST \G
mysql> SHOW FULL PROCESSLIST \G
*************************** 1. row ***************************
     Id: 1
   User: root
   Host: localhost:50756
     db: test
Command: Sleep
   Time: 232
  State:
   Info: NULL
*************************** 2. row ***************************
     Id: 3
   User: root
   Host: localhost:51561
     db: test
Command: Query
   Time: 0
  State: NULL
   Info: SHOW FULL PROCESSLIST
*************************** 3. row ***************************
     Id: 4
   User: event_scheduler
   Host: localhost
     db: NULL
Command: Daemon
   Time: 62
  State: Waiting for next activation
   Info: NULL
3 rows in set (0.00 sec)

开启 Event Scheduler，以下4种方式等效
SET GLOBAL event_scheduler = ON;
SET @@global.event_scheduler = ON;
SET GLOBAL event_scheduler = 1;
SET @@global.event_scheduler = 1;

关闭 Event Scheduler，以下4种方式等效
SET GLOBAL event_scheduler = OFF;
SET @@global.event_scheduler = OFF;
SET GLOBAL event_scheduler = 0;
SET @@global.event_scheduler = 0;

CREATE event语法
CREATE
    [DEFINER = { user | CURRENT_USER }]
    EVENT
    [IF NOT EXISTS]
    event_name
    ON SCHEDULE schedule
    [ON COMPLETION [NOT] PRESERVE]
    [ENABLE | DISABLE | DISABLE ON SLAVE]
    [COMMENT 'comment']
    DO event_body;

schedule:
    AT timestamp [+ INTERVAL interval] ...
  | EVERY interval
    [STARTS timestamp [+ INTERVAL interval] ...]
    [ENDS timestamp [+ INTERVAL interval] ...]

interval:
    quantity {YEAR | QUARTER | MONTH | DAY | HOUR | MINUTE |
              WEEK | SECOND | YEAR_MONTH | DAY_HOUR | DAY_MINUTE |
              DAY_SECOND | HOUR_MINUTE | HOUR_SECOND | MINUTE_SECOND}
具体含义可以参见mysql 5.5 Refer

查看event ddl
SHOW CREATE EVENT test_event;/SHOW CREATE EVENT test_event \G

查询schema下的所有event
SHOW EVENTS FROM test;/SHOW EVENTS FROM test \G
或
SELECT event_schema,event_name,event_definition,interval_value,interval_field,last_executed,status
FROM `INFORMATION_SCHEMA`.`EVENTS`
WHERE `EVENT_SCHEMA` = 'test'
ORDER BY EVENT_NAME;

--设置实例
mysql>  show variables like '%sched%';
+-----------------+-------+
| Variable_name   | Value |
+-----------------+-------+
| event_scheduler | OFF   |
+-----------------+-------+
1 row in set (0.00 sec)

mysql> select @@global.event_scheduler;
+--------------------------+
| @@global.event_scheduler |
+--------------------------+
| OFF                      |
+--------------------------+
1 row in set (0.00 sec)

mysql> SET GLOBAL event_scheduler = ON;
Query OK, 0 rows affected (0.02 sec)

mysql>  show variables like '%sched%';
+-----------------+-------+
| Variable_name   | Value |
+-----------------+-------+
| event_scheduler | ON    |
+-----------------+-------+
1 row in set (0.00 sec)

mysql> select @@global.event_scheduler;
+--------------------------+
| @@global.event_scheduler |
+--------------------------+
| ON                       |
+--------------------------+
1 row in set (0.00 sec)


--创建过程并生成event.
mysql> DELIMITER $$
mysql>
mysql> CREATE  PROCEDURE `test`.`test_proc_event`(IN p_date DATETIME)
    ->     BEGIN
    ->  START TRANSACTION;
    ->  INSERT INTO t_event VALUES(p_date);
    ->  COMMIT;
    ->     END$$
Query OK, 0 rows affected (0.00 sec)

mysql>
mysql> DELIMITER ;
mysql> delimiter //
mysql> create EVENT test_event
    ->     ON SCHEDULE
    ->     EVERY 2 MINUTE
    ->     do
    ->     begin
    ->       call test_proc_event(now());
    ->     end;
    ->     //
Query OK, 0 rows affected (0.00 sec)

--event生效
mysql> select * from t_event;
+---------------------+
| pdate               |
+---------------------+
| 2012-09-07 22:28:11 |
| 2012-09-07 22:30:11 |
| 2012-09-07 22:32:11 |
| 2012-09-07 22:34:11 |
+---------------------+
4 rows in set (0.00 sec)