系统表介绍
events_waits_history记录了历史等待事件，表中一行显示一个线程最近被监测到的等待事件。每个线程记录的数量受参数“performance_schema_events_waits_history_size” 控制
| 列名 | 含义 |
|---|---|
| THREAD_ID | 线程编号 |
| EVENT_ID | 事件编号 |
| END_EVENT_ID | 当事件结束后，发生启动修改线程当前事件号时置为空 |
| EVENT_NAME | 事件名称 |
| SOURCE | 包含监测器的源码文件 |
| TIMER_START | 事件启动的时间 |
| TIMER_END | 事件结束的时间 |
| TIMER_WAIT | 事件持续时长 TIMER_END-TIMER_START 单位是皮秒 百万分之一微秒 |
| SPINS | 自旋次数 |
| OBJECT_SCHEMA | 作用对象所属模式 |
| OBJECT_NAME | 作用对象名 |
| INDEX_NAME | 索引名 |
| OBJECT_TYPE | 对象类型 |
| OBJECT_INSTANCE_BEGIN | 对象内存地址 |
| NESTING_EVENT_ID | 嵌套事件编号 |
| NESTING_EVENT_TYPE | 嵌套事件类型 值为 TRANSACTION, STATEMENT, STAGE 或 WAIT. |
| OPERATION | 操作 |
| NUMBER_OF_BYTES | 操作读写的字节数 |
| FLAGS | 保留 |
实例
mysql> show variables like 'performance_schema_events_waits_history_size' ;
+----------------------------------------------+-------+
| Variable_name | Value |
+----------------------------------------------+-------+
| performance_schema_events_waits_history_size | 10 |
+----------------------------------------------+-------+
1 row in set (0.00 sec)
mysql> select * from events_waits_history limit 10;
+-----------+----------+--------------+--------------------------------------+--------+--------------------+--------------------+------------+-------+---------------+--------------------+------------+-------------+-----------------------+------------------+--------------------+-----------+-----------------+-------+
| THREAD_ID | EVENT_ID | END_EVENT_ID | EVENT_NAME | SOURCE | TIMER_START | TIMER_END | TIMER_WAIT | SPINS | OBJECT_SCHEMA | OBJECT_NAME | INDEX_NAME | OBJECT_TYPE | OBJECT_INSTANCE_BEGIN | NESTING_EVENT_ID | NESTING_EVENT_TYPE | OPERATION | NUMBER_OF_BYTES | FLAGS |
+-----------+----------+--------------+--------------------------------------+--------+--------------------+--------------------+------------+-------+---------------+--------------------+------------+-------------+-----------------------+------------------+--------------------+-----------+-----------------+-------+
| 13 | 271 | 271 | wait/io/file/innodb/innodb_data_file | | 391213723459666336 | 391213723513678736 | 54012400 | NULL | NULL | /data/mysql/ibtmp1 | NULL | FILE | 140391138327872 | NULL | NULL | write | 16384 | NULL |
| 13 | 272 | 272 | wait/io/file/innodb/innodb_data_file | | 391213723521667984 | 391213723539667856 | 17999872 | NULL | NULL | /data/mysql/ibtmp1 | NULL | FILE | 140391138327872 | NULL | NULL | write | 16384 | NULL |
| 13 | 273 | 273 | wait/io/file/innodb/innodb_data_file | | 391213723543985088 | 391213723560071120 | 16086032 | NULL | NULL | /data/mysql/ibtmp1 | NULL | FILE | 140391138327872 | NULL | NULL | write | 16384 | NULL |
| 13 | 264 | 264 | wait/io/file/innodb/innodb_data_file | | 389799643550687584 | 389799643591252720 | 40565136 | NULL | NULL | /data/mysql/ibtmp1 | NULL | FILE | 140391138327872 | NULL | NULL | write | 16384 | NULL |
| 13 | 265 | 265 | wait/io/file/innodb/innodb_data_file | | 391000970165945104 | 391000970285304800 | 119359696 | NULL | NULL | /data/mysql/ibtmp1 | NULL | FILE | 140391138327872 | NULL | NULL | write | 16384 | NULL |
| 13 | 266 | 266 | wait/io/file/innodb/innodb_data_file | | 391000970296657744 | 391000970401090240 | 104432496 | NULL | NULL | /data/mysql/ibtmp1 | NULL | FILE | 140391138327872 | NULL | NULL | write | 16384 | NULL |
| 13 | 267 | 267 | wait/io/file/innodb/innodb_data_file | | 391000970478594368 | 391000970525222880 | 46628512 | NULL | NULL | /data/mysql/ibtmp1 | NULL | FILE | 140391138327872 | NULL | NULL | write | 16384 | NULL |
| 13 | 268 | 268 | wait/io/file/innodb/innodb_data_file | | 391028067513623392 | 391028067576570304 | 62946912 | NULL | NULL | /data/mysql/ibtmp1 | NULL | FILE | 140391138327872 | NULL | NULL | write | 16384 | NULL |
| 13 | 269 | 269 | wait/io/file/innodb/innodb_data_file | | 391028067583606768 | 391028067606595408 | 22988640 | NULL | NULL | /data/mysql/ibtmp1 | NULL | FILE | 140391138327872 | NULL | NULL | write | 16384 | NULL |
| 13 | 270 | 270 | wait/io/file/innodb/innodb_data_file | | 391028067612175248 | 391028067633612512 | 21437264 | NULL | NULL | /data/mysql/ibtmp1 | NULL | FILE | 140391138327872 | NULL | NULL | write | 16384 | NULL |
+-----------+----------+--------------+--------------------------------------+--------+--------------------+--------------------+------------+-------+---------------+--------------------+------------+-------------+-----------------------+------------------+--------------------+-----------+-----------------+-------+
10 rows in set (0.00 sec)