怎么理解MySQL5.6中的PERFORMANCE_SCHEM

本篇内容介绍了“怎么理解MySQL5.6中的PERFORMANCE_SCHEM”的有关知识，在实际案例的操作过程中，不少人都会遇到这样的困境，接下来就让小编带领大家学习一下如何处理这些情况吧！希望大家仔细阅读，能够学有所成！

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通过sql语句找到在经历什么等待事件!

Statement -> stage -> wait的三级结构，通过nesting_event_id进行关联，它表示某个事件的父event_id。

比如分析包含count(*)的某条SQL语句，具体如下：(类似于oracle的v$sql, v$sqlstat, v$sqlarea)

SELECT

EVENT_ID,

sql_text

FROM events_statements_history

WHERE sql_text LIKE '%count(*)%';

+----------+--------------------------------------+

| EVENT_ID | sql_text |

+----------+--------------------------------------+

| 1690 | select count(*) from chuck.test_slow |

+----------+--------------------------------------+

a.查看每个阶段的时间消耗：(类似于oracle的时间模型V$SYS_TIME_MODEL V$SESS_TIME_MODEL)

SELECT

event_id,

EVENT_NAME,

SOURCE,

TIMER_END - TIMER_START

FROM events_stages_history_long

WHERE NESTING_EVENT_ID = 1690;

+----------+--------------------------------+----------------------+-----------------------+

+----------+--------------------------------+----------------------+-----------------------+

……

| 2647 | stage/sql/Sending data | sql_executor.cc:192 | 7369072089000 |

b.查看某个阶段的锁等待情况 (类似于oracle的v$session_wait)

针对每个stage可能出现的锁等待，一个stage会对应一个或多个wait，events_waits_history_long这个表容易爆满[默认阀值10000]。由于select count(*)需要IO(逻辑IO或者物理IO)，所以在stage/sql/Sending data阶段会有io等待的统计。通过stage_xxx表的event_id字段与waits_xxx表的nesting_event_id进行关联。

SELECT

event_id,

event_name,

source,

timer_wait,

object_name,

index_name,

operation,

nesting_event_id

FROM events_waits_history_long

WHERE nesting_event_id = 2647;

+----------+---------------------------+-----------------+------------+-------------+------------+-----------+------------------+

+----------+---------------------------+-----------------+------------+-------------+------------+-----------+------------------+

https://www.cnblogs.com/zhoujinyi/p/5236705.html

MySQL5.6 PERFORMANCE_SCHEMA 说明

背景：

MySQL 5.5开始新增一个数据库：PERFORMANCE_SCHEMA，主要用于收集数据库服务器性能参数。并且库里表的存储引擎均为PERFORMANCE_SCHEMA，而用户是不能创建存储引擎为PERFORMANCE_SCHEMA的表。MySQL5.5默认是关闭的，需要手动开启，在配置文件里添加：

[mysqld]

performance_schema=ON

查看是否开启：

mysql>show variables like 'performance_schema';

+--------------------+-------+

| Variable_name | Value |

+--------------------+-------+

| performance_schema | ON |

+--------------------+-------+

从MySQL5.6开始，默认打开，本文就从MySQL5.6来说明，在数据库使用当中PERFORMANCE_SCHEMA的一些比较常用的功能。具体的信息可以查看官方文档。

相关表信息：

一：配置（setup）表：

zjy@performance_schema 10:16:56>show tables like '%setup%';

+----------------------------------------+

| Tables_in_performance_schema (%setup%) |

+----------------------------------------+

| setup_actors |

| setup_consumers |

| setup_instruments |

| setup_objects |

| setup_timers |

+----------------------------------------+

1，setup_actors：配置用户纬度的监控，默认监控所有用户。

zjy@performance_schema 10:19:11>select * from setup_actors;

+------+------+------+

| HOST | USER | ROLE |

+------+------+------+

| % | % | % |

+------+------+------+

2，setup_consumers：配置events的消费者类型，即收集的events写入到哪些统计表中。

zjy@: performance_schema 10:23:35>select * from setup_consumers;

+--------------------------------+---------+

| NAME | ENABLED |

+--------------------------------+---------+

| events_stages_current | NO |

| events_stages_history | NO |

| events_stages_history_long | NO |

| events_statements_current | YES |

| events_statements_history | NO |

| events_statements_history_long | NO |

| events_waits_current | NO |

| events_waits_history | NO |

| events_waits_history_long | NO |

| global_instrumentation | YES |

| thread_instrumentation | YES |

| statements_digest | YES |

+--------------------------------+---------+

这里需要说明的是需要查看哪个就更新其ENABLED列为YES。如：

zjy@performance_schema 10:25:02>update setup_consumers set ENABLED='YES' where NAME in ('events_stages_current','events_waits_current');

Query OK, 2 rows affected (0.00 sec)

更新完后立即生效，但是服务器重启之后又会变回默认值，要永久生效需要在配置文件里添加：

[mysqld]

#performance_schema

performance_schema_consumer_events_waits_current=on

performance_schema_consumer_events_stages_current=on

performance_schema_consumer_events_statements_current=on

performance_schema_consumer_events_waits_history=on

performance_schema_consumer_events_stages_history=on

performance_schema_consumer_events_statements_history=on

即在这些表的前面加上：performance_schema_consumer_xxx。表setup_consumers里面的值有个层级关系：

global_instrumentation > thread_instrumentation = statements_digest > events_stages_current = events_statements_current = events_waits_current > events_stages_history = events_statements_history = events_waits_history > events_stages_history_long = events_statements_history_long = events_waits_history_long

只有上一层次的为YES，才会继续检查该本层为YES or NO。global_instrumentation是最高级别consumer，如果它设置为NO，则所有的consumer都会忽略。其中history和history_long存的是current表的历史记录条数，history表记录了每个线程最近等待的10个事件，而history_long表则记录了最近所有线程产生的10000个事件，这里的10和10000都是可以配置的。这三个表表结构相同，history和history_long表数据都来源于current表。长度通过控制参数：

zjy@performance_schema 11:10:03>show variables like 'performance_schema%history%size';

+--------------------------------------------------------+-------+

| Variable_name | Value |

+--------------------------------------------------------+-------+

| performance_schema_events_stages_history_long_size | 10000 |

| performance_schema_events_stages_history_size | 10 |

| performance_schema_events_statements_history_long_size | 10000 |

| performance_schema_events_statements_history_size | 10 |

| performance_schema_events_waits_history_long_size | 10000 |

| performance_schema_events_waits_history_size | 10 |

+--------------------------------------------------------+-------+

3，setup_instruments：配置具体的instrument，主要包含4大类：idle、stage/xxx、statement/xxx、wait/xxx：

zjy@performance_schema 10:56:35>select name,count(*) from setup_instruments group by LEFT(name,5);

+---------------------------------+----------+

| name | count(*) |

+---------------------------------+----------+

| idle | 1 |

| stage/sql/After create | 111 |

| statement/sql/select | 179 |

| wait/synch/mutex/sql/PAGE::lock | 296 |

+---------------------------------+----------+

idle表示socket空闲的时间，stage类表示语句的每个执行阶段的统计，statement类统计语句维度的信息，wait类统计各种等待事件，比如IO，mutux，spin_lock,condition等。

4，setup_objects：配置监控对象，默认对mysql，performance_schema和information_schema中的表都不监控，而其它DB的所有表都监控。

zjy@performance_schema 11:00:18>select * from setup_objects;

+-------------+--------------------+-------------+---------+-------+

+-------------+--------------------+-------------+---------+-------+

| TABLE | mysql | % | NO | NO |

| TABLE | performance_schema | % | NO | NO |

| TABLE | information_schema | % | NO | NO |

| TABLE | % | % | YES | YES |

+-------------+--------------------+-------------+---------+-------+

5，setup_timers：配置每种类型指令的统计时间单位。MICROSECOND表示统计单位是微妙，CYCLE表示统计单位是时钟周期，时间度量与CPU的主频有关，NANOSECOND表示统计单位是纳秒。但无论采用哪种度量单位，最终统计表中统计的时间都会装换到皮秒。（1秒＝1000000000000皮秒）

zjy@performance_schema 11:05:12>select * from setup_timers;

+-----------+-------------+

| NAME | TIMER_NAME |

+-----------+-------------+

| idle | MICROSECOND |

| wait | CYCLE |

| stage | NANOSECOND |

| statement | NANOSECOND |

+-----------+-------------+

二：instance表

1，cond_instances：条件等待对象实例

表中记录了系统中使用的条件变量的对象，OBJECT_INSTANCE_BEGIN为对象的内存地址。

2，file_instances：文件实例

表中记录了系统中打开了文件的对象，包括ibdata文件，redo文件，binlog文件，用户的表文件等，open_count显示当前文件打开的数目，如果重来没有打开过，不会出现在表中。

zjy@performance_schema 11:20:04>select * from file_instances limit 2,5;

+---------------------------------+--------------------------------------+------------+

| FILE_NAME | EVENT_NAME | OPEN_COUNT |

+---------------------------------+--------------------------------------+------------+

| /var/lib/mysql/mysql/plugin.frm | wait/io/file/sql/FRM | |

| /var/lib/mysql/mysql/plugin.MYI | wait/io/file/myisam/kfile | 1 |

| /var/lib/mysql/mysql/plugin.MYD | wait/io/file/myisam/dfile | 1 |

| /var/lib/mysql/ibdata1 | wait/io/file/innodb/innodb_data_file | 2 |

| /var/lib/mysql/ib_logfile0 | wait/io/file/innodb/innodb_log_file | 2 |

+---------------------------------+--------------------------------------+------------+

3，mutex_instances：互斥同步对象实例

表中记录了系统中使用互斥量对象的所有记录，其中name为：wait/synch/mutex/*。LOCKED_BY_THREAD_ID显示哪个线程正持有mutex，若没有线程持有，则为NULL。

4，rwlock_instances： 读写锁同步对象实例

表中记录了系统中使用读写锁对象的所有记录，其中name为 wait/synch/rwlock/*。WRITE_LOCKED_BY_THREAD_ID为正在持有该对象的thread_id，若没有线程持有，则为NULL。READ_LOCKED_BY_COUNT为记录了同时有多少个读者持有读锁。（通过 events_waits_current 表可以知道，哪个线程在等待锁；通过rwlock_instances知道哪个线程持有锁。rwlock_instances的缺陷是，只能记录持有写锁的线程，对于读锁则无能为力）。

5，socket_instances：活跃会话对象实例
表中记录了thread_id,socket_id,ip和port，其它表可以通过thread_id与socket_instance进行关联，获取IP-PORT信息，能够与应用对接起来。
event_name主要包含3类：
wait/io/socket/sql/server_unix_socket，服务端unix监听socket
wait/io/socket/sql/server_tcpip_socket，服务端tcp监听socket
wait/io/socket/sql/client_connection，客户端socket

三：Wait表

1，events_waits_current：记录了当前线程等待的事件

2，events_waits_history：记录了每个线程最近等待的10个事件

3，events_waits_history_long：记录了最近所有线程产生的10000个事件

表结构定义如下：

CREATE TABLE `events_waits_current` (

`THREAD_ID` bigint(20) unsigned NOT NULL COMMENT '线程ID',

`EVENT_ID` bigint(20) unsigned NOT NULL COMMENT '当前线程的事件ID，和THREAD_ID确定唯一',

`END_EVENT_ID` bigint(20) unsigned DEFAULT NULL COMMENT '当事件开始时，这一列被设置为NULL。当事件结束时，再更新为当前的事件ID',

`EVENT_NAME` varchar(128) NOT NULL COMMENT '事件名称',

`SOURCE` varchar(64) DEFAULT NULL COMMENT '该事件产生时的源码文件',

`TIMER_START` bigint(20) unsigned DEFAULT NULL COMMENT '事件开始时间（皮秒）',

`TIMER_END` bigint(20) unsigned DEFAULT NULL COMMENT '事件结束结束时间（皮秒）',

`TIMER_WAIT` bigint(20) unsigned DEFAULT NULL COMMENT '事件等待时间（皮秒）',

`SPINS` int(10) unsigned DEFAULT NULL COMMENT '',

`OBJECT_SCHEMA` varchar(64) DEFAULT NULL COMMENT '库名',

`OBJECT_NAME` varchar(512) DEFAULT NULL COMMENT '文件名、表名、IP:SOCK值',

`OBJECT_TYPE` varchar(64) DEFAULT NULL COMMENT 'FILE、TABLE、TEMPORARY TABLE',

`INDEX_NAME` varchar(64) DEFAULT NULL COMMENT '索引名',

`OBJECT_INSTANCE_BEGIN` bigint(20) unsigned NOT NULL COMMENT '内存地址',

`NESTING_EVENT_ID` bigint(20) unsigned DEFAULT NULL COMMENT '该事件对应的父事件ID',

`NESTING_EVENT_TYPE` enum('STATEMENT','STAGE','WAIT') DEFAULT NULL COMMENT '父事件类型(STATEMENT, STAGE, WAIT)',

`OPERATION` varchar(32) NOT NULL COMMENT '操作类型（lock, read, write）',

`NUMBER_OF_BYTES` bigint(20) DEFAULT NULL COMMENT '',

`FLAGS` int(10) unsigned DEFAULT NULL COMMENT '标记'

) ENGINE=PERFORMANCE_SCHEMA DEFAULT CHARSET=utf8

四：Stage 表

1，events_stages_current：记录了当前线程所处的执行阶段

2，events_stages_history：记录了当前线程所处的执行阶段10条历史记录

3，events_stages_history_long：记录了当前线程所处的执行阶段10000条历史记录

表结构定义如下：

CREATE TABLE `events_stages_current` (

`THREAD_ID` bigint(20) unsigned NOT NULL COMMENT '线程ID',

`EVENT_ID` bigint(20) unsigned NOT NULL COMMENT '事件ID',

`END_EVENT_ID` bigint(20) unsigned DEFAULT NULL COMMENT '结束事件ID',

`EVENT_NAME` varchar(128) NOT NULL COMMENT '事件名称',

`SOURCE` varchar(64) DEFAULT NULL COMMENT '源码位置',

`TIMER_START` bigint(20) unsigned DEFAULT NULL COMMENT '事件开始时间（皮秒）',

`TIMER_END` bigint(20) unsigned DEFAULT NULL COMMENT '事件结束结束时间（皮秒）',

`TIMER_WAIT` bigint(20) unsigned DEFAULT NULL COMMENT '事件等待时间（皮秒）',

`NESTING_EVENT_ID` bigint(20) unsigned DEFAULT NULL COMMENT '该事件对应的父事件ID',

`NESTING_EVENT_TYPE` enum('STATEMENT','STAGE','WAIT') DEFAULT NULL COMMENT '父事件类型(STATEMENT, STAGE, WAIT)'

) ENGINE=PERFORMANCE_SCHEMA DEFAULT CHARSET=utf8

五：Statement 表

1，events_statements_current：通过 thread_id+event_id可以唯一确定一条记录。Statments表只记录最顶层的请求，SQL语句或是COMMAND，每条语句一行。event_name形式为statement/sql/*，或statement/com/*

2，events_statements_history

3，events_statements_history_long

表结构定义如下：

CREATE TABLE `events_statements_current` (

`THREAD_ID` bigint(20) unsigned NOT NULL COMMENT '线程ID',

`EVENT_ID` bigint(20) unsigned NOT NULL COMMENT '事件ID',

`END_EVENT_ID` bigint(20) unsigned DEFAULT NULL COMMENT '结束事件ID',

`EVENT_NAME` varchar(128) NOT NULL COMMENT '事件名称',

`SOURCE` varchar(64) DEFAULT NULL COMMENT '源码位置',

`TIMER_START` bigint(20) unsigned DEFAULT NULL COMMENT '事件开始时间（皮秒）',

`TIMER_END` bigint(20) unsigned DEFAULT NULL COMMENT '事件结束结束时间（皮秒）',

`TIMER_WAIT` bigint(20) unsigned DEFAULT NULL COMMENT '事件等待时间（皮秒）',

`LOCK_TIME` bigint(20) unsigned NOT NULL COMMENT '锁时间',

`SQL_TEXT` longtext COMMENT '记录SQL语句',

`DIGEST` varchar(32) DEFAULT NULL COMMENT '对SQL_TEXT做MD5产生的32位字符串',

`DIGEST_TEXT` longtext COMMENT '将语句中值部分用问号代替，用于SQL语句归类',

`CURRENT_SCHEMA` varchar(64) DEFAULT NULL COMMENT '默认的数据库名',

`OBJECT_TYPE` varchar(64) DEFAULT NULL COMMENT '保留字段',

`OBJECT_SCHEMA` varchar(64) DEFAULT NULL COMMENT '保留字段',

`OBJECT_NAME` varchar(64) DEFAULT NULL COMMENT '保留字段',

`OBJECT_INSTANCE_BEGIN` bigint(20) unsigned DEFAULT NULL COMMENT '内存地址',

`MYSQL_ERRNO` int(11) DEFAULT NULL COMMENT '',

`RETURNED_SQLSTATE` varchar(5) DEFAULT NULL COMMENT '',

`MESSAGE_TEXT` varchar(128) DEFAULT NULL COMMENT '信息',

`ERRORS` bigint(20) unsigned NOT NULL COMMENT '错误数目',

`WARNINGS` bigint(20) unsigned NOT NULL COMMENT '警告数目',

`ROWS_AFFECTED` bigint(20) unsigned NOT NULL COMMENT '影响的数目',

`ROWS_SENT` bigint(20) unsigned NOT NULL COMMENT '返回的记录数',

`ROWS_EXAMINED` bigint(20) unsigned NOT NULL COMMENT '读取扫描的记录数目',

`CREATED_TMP_DISK_TABLES` bigint(20) unsigned NOT NULL COMMENT '创建磁盘临时表数目',

`CREATED_TMP_TABLES` bigint(20) unsigned NOT NULL COMMENT '创建临时表数目',

`SELECT_FULL_JOIN` bigint(20) unsigned NOT NULL COMMENT 'join时，第一个表为全表扫描的数目',

`SELECT_FULL_RANGE_JOIN` bigint(20) unsigned NOT NULL COMMENT '引用表采用range方式扫描的数目',

`SELECT_RANGE` bigint(20) unsigned NOT NULL COMMENT 'join时，第一个表采用range方式扫描的数目',

`SELECT_RANGE_CHECK` bigint(20) unsigned NOT NULL COMMENT '',

`SELECT_SCAN` bigint(20) unsigned NOT NULL COMMENT 'join时，第一个表位全表扫描的数目',

`SORT_MERGE_PASSES` bigint(20) unsigned NOT NULL COMMENT '',

`SORT_RANGE` bigint(20) unsigned NOT NULL COMMENT '范围排序数目',

`SORT_ROWS` bigint(20) unsigned NOT NULL COMMENT '排序的记录数目',

`SORT_SCAN` bigint(20) unsigned NOT NULL COMMENT '全表排序数目',

`NO_INDEX_USED` bigint(20) unsigned NOT NULL COMMENT '没有使用索引数目',

`NO_GOOD_INDEX_USED` bigint(20) unsigned NOT NULL COMMENT '',

`NESTING_EVENT_ID` bigint(20) unsigned DEFAULT NULL COMMENT '该事件对应的父事件ID',

`NESTING_EVENT_TYPE` enum('STATEMENT','STAGE','WAIT') DEFAULT NULL COMMENT '父事件类型(STATEMENT, STAGE, WAIT)'

) ENGINE=PERFORMANCE_SCHEMA DEFAULT CHARSET=utf8

六：Connection 表

1，users：记录用户连接数信息

2，hosts：记录了主机连接数信息

3，accounts：记录了用户主机连接数信息

zjy@performance_schema 12:03:27>select * from users;

+------------------+---------------------+-------------------+

| USER | CURRENT_CONNECTIONS | TOTAL_CONNECTIONS |

+------------------+---------------------+-------------------+

| debian-sys-maint | | 36 |

| zjy | 1 | 22285 |

| dchat_php | | 37864 |

| dxyslave | 2 | 9 |

| nagios | | 10770 |

| dchat_data | 140 | 2233023 |

| NULL | | 15866 |

| dchat_api | 160 | 2754212 |

| mha_data | 1 | 36 |

| backup | | 15 |

| cacti | | 4312 |

| kol | 10 | 172414 |

+------------------+---------------------+-------------------+

12 rows in set (0.00 sec)

zjy@performance_schema 12:03:34>select * from hosts;

+-----------------+---------------------+-------------------+

| HOST | CURRENT_CONNECTIONS | TOTAL_CONNECTIONS |

+-----------------+---------------------+-------------------+

| 192.168.100.218 | 150 | 2499422 |

| 192.168.100.240 | 10 | 172429 |

| 192.168.100.139 | | 698 |

| 192.168.100.21 | | 2 |

| 192.168.100.220 | 150 | 2526136 |

| 192.168.100.25 | 1 | 7 |

| NULL | | 15867 |

| 192.168.100.241 | | 21558 |

| 192.168.100.191 | 1 | 34 |

| localhost | | 10807 |

| 192.168.100.118 | 1 | 2 |

| 192.168.100.251 | | 4312 |

| 192.168.100.23 | 1 | 31 |

| 192.168.100.193 | | 15 |

+-----------------+---------------------+-------------------+

14 rows in set (0.01 sec)

zjy@performance_schema 12:05:21>select * from accounts;

+------------------+-----------------+---------------------+-------------------+

+------------------+-----------------+---------------------+-------------------+

| cacti | 192.168.100.251 | | 4313 |

| backup | 192.168.100.193 | | 15 |

| dchat_api | 192.168.100.220 | 80 | 1382585 |

| dchat_php | 192.168.100.220 | | 20292 |

| zjy | 192.168.100.139 | | 698 |

| zjy | 192.168.100.241 | | 21558 |

| mha_data | 192.168.100.191 | 1 | 34 |

| dxyslave | 192.168.100.118 | 1 | 2 |

| kol | 192.168.100.240 | 10 | 172431 |

| dxyslave | 192.168.100.25 | 1 | 7 |

| dchat_data | 192.168.100.218 | 70 | 1109974 |

| zjy | 192.168.100.23 | 1 | 31 |

| dchat_php | 192.168.100.218 | | 17572 |

| dchat_data | 192.168.100.220 | 70 | 1123306 |

| mha_data | 192.168.100.21 | | 2 |

| dchat_api | 192.168.100.218 | 80 | 1371918 |

+------------------+-----------------+---------------------+-------------------+

View Code

七：Summary 表： Summary表聚集了各个维度的统计信息包括表维度，索引维度，会话维度，语句维度和锁维度的统计信息

1，events_waits_summary_global_by_event_name：按等待事件类型聚合，每个事件一条记录

CREATE TABLE `events_waits_summary_global_by_event_name` (

`EVENT_NAME` varchar(128) NOT NULL COMMENT '事件名称',

`COUNT_STAR` bigint(20) unsigned NOT NULL COMMENT '事件计数',

`SUM_TIMER_WAIT` bigint(20) unsigned NOT NULL COMMENT '总的等待时间',

`MIN_TIMER_WAIT` bigint(20) unsigned NOT NULL COMMENT '最小等待时间',

`AVG_TIMER_WAIT` bigint(20) unsigned NOT NULL COMMENT '平均等待时间',

`MAX_TIMER_WAIT` bigint(20) unsigned NOT NULL COMMENT '最大等待时间'

) ENGINE=PERFORMANCE_SCHEMA DEFAULT CHARSET=utf8

2，events_waits_summary_by_instance：按等待事件对象聚合，同一种等待事件，可能有多个实例，每个实例有不同的内存地址，因此
event_name+object_instance_begin唯一确定一条记录。

CREATE TABLE `events_waits_summary_by_instance` (

`EVENT_NAME` varchar(128) NOT NULL COMMENT '事件名称',

`OBJECT_INSTANCE_BEGIN` bigint(20) unsigned NOT NULL COMMENT '内存地址',

`COUNT_STAR` bigint(20) unsigned NOT NULL COMMENT '事件计数',

`SUM_TIMER_WAIT` bigint(20) unsigned NOT NULL COMMENT '总的等待时间',

`MIN_TIMER_WAIT` bigint(20) unsigned NOT NULL COMMENT '最小等待时间',

`AVG_TIMER_WAIT` bigint(20) unsigned NOT NULL COMMENT '平均等待时间',

`MAX_TIMER_WAIT` bigint(20) unsigned NOT NULL COMMENT '最大等待时间'

) ENGINE=PERFORMANCE_SCHEMA DEFAULT CHARSET=utf8

3，events_waits_summary_by_thread_by_event_name：按每个线程和事件来统计，thread_id+event_name唯一确定一条记录。

CREATE TABLE `events_waits_summary_by_thread_by_event_name` (

`THREAD_ID` bigint(20) unsigned NOT NULL COMMENT '线程ID',

`EVENT_NAME` varchar(128) NOT NULL COMMENT '事件名称',

`COUNT_STAR` bigint(20) unsigned NOT NULL COMMENT '事件计数',

`SUM_TIMER_WAIT` bigint(20) unsigned NOT NULL COMMENT '总的等待时间',

`MIN_TIMER_WAIT` bigint(20) unsigned NOT NULL COMMENT '最小等待时间',

`AVG_TIMER_WAIT` bigint(20) unsigned NOT NULL COMMENT '平均等待时间',

`MAX_TIMER_WAIT` bigint(20) unsigned NOT NULL COMMENT '最大等待时间'

) ENGINE=PERFORMANCE_SCHEMA DEFAULT CHARSET=utf8

4，events_stages_summary_global_by_event_name：按事件阶段类型聚合，每个事件一条记录，表结构同上。

5，events_stages_summary_by_thread_by_event_name：按每个线程和事件来阶段统计，表结构同上。

6，events_statements_summary_by_digest：按照事件的语句进行聚合。

CREATE TABLE `events_statements_summary_by_digest` (

`SCHEMA_NAME` varchar(64) DEFAULT NULL COMMENT '库名',

`DIGEST` varchar(32) DEFAULT NULL COMMENT '对SQL_TEXT做MD5产生的32位字符串。如果为consumer表中没有打开statement_digest选项，则为NULL',

`DIGEST_TEXT` longtext COMMENT '将语句中值部分用问号代替，用于SQL语句归类。如果为consumer表中没有打开statement_digest选项，则为NULL。',

`COUNT_STAR` bigint(20) unsigned NOT NULL COMMENT '事件计数',

`SUM_TIMER_WAIT` bigint(20) unsigned NOT NULL COMMENT '总的等待时间',

`MIN_TIMER_WAIT` bigint(20) unsigned NOT NULL COMMENT '最小等待时间',

`AVG_TIMER_WAIT` bigint(20) unsigned NOT NULL COMMENT '平均等待时间',

`MAX_TIMER_WAIT` bigint(20) unsigned NOT NULL COMMENT '最大等待时间',

`SUM_LOCK_TIME` bigint(20) unsigned NOT NULL COMMENT '锁时间总时长',

`SUM_ERRORS` bigint(20) unsigned NOT NULL COMMENT '错误数的总',

`SUM_WARNINGS` bigint(20) unsigned NOT NULL COMMENT '警告的总数',

`SUM_ROWS_AFFECTED` bigint(20) unsigned NOT NULL COMMENT '影响的总数目',

`SUM_ROWS_SENT` bigint(20) unsigned NOT NULL COMMENT '返回总数目',

`SUM_ROWS_EXAMINED` bigint(20) unsigned NOT NULL COMMENT '总的扫描的数目',

`SUM_CREATED_TMP_DISK_TABLES` bigint(20) unsigned NOT NULL COMMENT '创建磁盘临时表的总数目',

`SUM_CREATED_TMP_TABLES` bigint(20) unsigned NOT NULL COMMENT '创建临时表的总数目',

`SUM_SELECT_FULL_JOIN` bigint(20) unsigned NOT NULL COMMENT '第一个表全表扫描的总数目',

`SUM_SELECT_FULL_RANGE_JOIN` bigint(20) unsigned NOT NULL COMMENT '总的采用range方式扫描的数目',

`SUM_SELECT_RANGE` bigint(20) unsigned NOT NULL COMMENT '第一个表采用range方式扫描的总数目',

`SUM_SELECT_RANGE_CHECK` bigint(20) unsigned NOT NULL COMMENT '',

`SUM_SELECT_SCAN` bigint(20) unsigned NOT NULL COMMENT '第一个表位全表扫描的总数目',

`SUM_SORT_MERGE_PASSES` bigint(20) unsigned NOT NULL COMMENT '',

`SUM_SORT_RANGE` bigint(20) unsigned NOT NULL COMMENT '范围排序总数',

`SUM_SORT_ROWS` bigint(20) unsigned NOT NULL COMMENT '排序的记录总数目',

`SUM_SORT_SCAN` bigint(20) unsigned NOT NULL COMMENT '第一个表排序扫描总数目',

`SUM_NO_INDEX_USED` bigint(20) unsigned NOT NULL COMMENT '没有使用索引总数',

`SUM_NO_GOOD_INDEX_USED` bigint(20) unsigned NOT NULL COMMENT '',

`FIRST_SEEN` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00' COMMENT '第一次执行时间',

`LAST_SEEN` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00' COMMENT '最后一次执行时间'

) ENGINE=PERFORMANCE_SCHEMA DEFAULT CHARSET=utf8

7，events_statements_summary_global_by_event_name：按照事件的语句进行聚合。表结构同上。

8，events_statements_summary_by_thread_by_event_name：按照线程和事件的语句进行聚合，表结构同上。

9，file_summary_by_instance：按事件类型统计（物理IO维度）

10，file_summary_by_event_name：具体文件统计（物理IO维度）

9和10一起说明：

统计IO操作：COUNT_STAR，SUM_TIMER_WAIT,MIN_TIMER_WAIT,AVG_TIMER_WAIT,MAX_TIMER_WAIT

统计读：COUNT_READ,SUM_TIMER_READ,MIN_TIMER_READ,AVG_TIMER_READ,MAX_TIMER_READ, SUM_NUMBER_OF_BYTES_READ

统计写：COUNT_WRITE,SUM_TIMER_WRITE,MIN_TIMER_WRITE,AVG_TIMER_WRITE,MAX_TIMER_WRITE, SUM_NUMBER_OF_BYTES_WRITE

统计其他IO事件，比如create，delete，open，close等：COUNT_MISC,SUM_TIMER_MISC,MIN_TIMER_MISC,AVG_TIMER_MISC,MAX_TIMER_MISC

11，table_io_waits_summary_by_table：根据wait/io/table/sql/handler，聚合每个表的I/O操作（逻辑IO纬度）

统计IO操作：COUNT_STAR,SUM_TIMER_WAIT,MIN_TIMER_WAIT,AVG_TIMER_WAIT,MAX_TIMER_WAIT

统计读：COUNT_READ,SUM_TIMER_READ,MIN_TIMER_READ,AVG_TIMER_READ,MAX_TIMER_READ

：COUNT_FETCH,SUM_TIMER_FETCH,MIN_TIMER_FETCH,AVG_TIMER_FETCH, MAX_TIMER_FETCH

统计写：COUNT_WRITE,SUM_TIMER_WRITE,MIN_TIMER_WRITE,AVG_TIMER_WRITE,MAX_TIMER_WRITE

INSERT统计，相应的还有DELETE和UPDATE统计：COUNT_INSERT,SUM_TIMER_INSERT,MIN_TIMER_INSERT,AVG_TIMER_INSERT,MAX_TIMER_INSERT

12，table_io_waits_summary_by_index_usage：与table_io_waits_summary_by_table类似，按索引维度统计

13，table_lock_waits_summary_by_table：聚合了表锁等待事件，包括internal lock 和 external lock

internal lock通过SQL层函数thr_lock调用，OPERATION值为：
read normal、read with shared locks、read high priority、read no insert、write allow write、write concurrent insert、write delayed、write low priority、write normal
external lock则通过接口函数handler::external_lock调用存储引擎层，OPERATION列的值为：read external、write external

14，Connection Summaries表：account、user、host

events_waits_summary_by_account_by_event_name
events_waits_summary_by_user_by_event_name
events_waits_summary_by_host_by_event_name
events_stages_summary_by_account_by_event_name
events_stages_summary_by_user_by_event_name
events_stages_summary_by_host_by_event_name
events_statements_summary_by_account_by_event_name
events_statements_summary_by_user_by_event_name
events_statements_summary_by_host_by_event_name

15，socket_summary_by_instance、socket_summary_by_event_name：socket聚合统计表。

八：其他相关表

1，performance_timers：系统支持的统计时间单位

2，threads：监视服务端的当前运行的线程

统计应用：

关于SQL维度的统计信息主要集中在events_statements_summary_by_digest表中，通过将SQL语句抽象出digest，可以统计某类SQL语句在各个维度的统计信息

1，哪个SQL执行最多：

zjy@performance_schema 11:36:22>SELECT SCHEMA_NAME,DIGEST_TEXT,COUNT_STAR,SUM_ROWS_SENT,SUM_ROWS_EXAMINED,FIRST_SEEN,LAST_SEEN FROM events_statements_summary_by_digest ORDER BY COUNT_STAR desc LIMIT 1\G

*************************** 1. row ***************************

SCHEMA_NAME: dchat

DIGEST_TEXT: SELECT ...

COUNT_STAR: 1161210102

SUM_ROWS_SENT: 1161207842

SUM_ROWS_EXAMINED:

FIRST_SEEN: 2016-02-17 00:36:46

LAST_SEEN: 2016-03-07 11:36:29

各个字段的注释可以看上面的表结构说明：从2月17号到3月7号该SQL执行了1161210102次。

2，哪个SQL平均响应时间最多：

zjy@performance_schema 11:36:28>SELECT SCHEMA_NAME,DIGEST_TEXT,COUNT_STAR,AVG_TIMER_WAIT,SUM_ROWS_SENT,SUM_ROWS_EXAMINED,FIRST_SEEN,LAST_SEEN FROM events_statements_summary_by_digest ORDER BY AVG_TIMER_WAIT desc LIMIT 1\G

*************************** 1. row ***************************

SCHEMA_NAME: dchat

DIGEST_TEXT: SELECT ...

COUNT_STAR: 1

AVG_TIMER_WAIT: 273238183964000

SUM_ROWS_SENT: 50208

SUM_ROWS_EXAMINED: 5565651

FIRST_SEEN: 2016-02-22 13:27:33

LAST_SEEN: 2016-02-22 13:27:33

各个字段的注释可以看上面的表结构说明：从2月17号到3月7号该SQL平均响应时间273238183964000皮秒（1000000000000皮秒=1秒）

3，哪个SQL扫描的行数最多：

SUM_ROWS_EXAMINED

4，哪个SQL使用的临时表最多：

SUM_CREATED_TMP_DISK_TABLES、SUM_CREATED_TMP_TABLES

5，哪个SQL返回的结果集最多：

SUM_ROWS_SENT

6，哪个SQL排序数最多：

SUM_SORT_ROWS

通过上述指标我们可以间接获得某类SQL的逻辑IO(SUM_ROWS_EXAMINED)，CPU消耗(SUM_SORT_ROWS)，网络带宽(SUM_ROWS_SENT)的对比。

通过file_summary_by_instance表，可以获得系统运行到现在，哪个文件(表)物理IO最多，这可能意味着这个表经常需要访问磁盘IO。

7，哪个表、文件逻辑IO最多（热数据）：

zjy@performance_schema 12:16:18>SELECT FILE_NAME,EVENT_NAME,COUNT_READ,SUM_NUMBER_OF_BYTES_READ,COUNT_WRITE,SUM_NUMBER_OF_BYTES_WRITE FROM file_summary_by_instance ORDER BY SUM_NUMBER_OF_BYTES_READ+SUM_NUMBER_OF_BYTES_WRITE DESC LIMIT 2\G

*************************** 1. row ***************************

FILE_NAME: /var/lib/mysql/ibdata1 #文件

本文名称：怎么理解MySQL5.6中的PERFORMANCE_SCHEM
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