MySQL5.6 PERFORMANCE_SCHEMA 说明
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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;
+-------------+--------------------+-------------+---------+-------+
| OBJECT_TYPE | OBJECT_SCHEMA | OBJECT_NAME | ENABLED | TIMED |
+-------------+--------------------+-------------+---------+-------+
| 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 | 0 |
| /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
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: 0
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
EVENT_NAME: wait/io/file/innodb/innodb_data_file
COUNT_READ: 544
SUM_NUMBER_OF_BYTES_READ: 10977280
COUNT_WRITE: 3700729
SUM_NUMBER_OF_BYTES_WRITE: 1433734217728
*************************** 2. row ***************************
FILE_NAME: /var/lib/mysql/dchat/fans.ibd #表
EVENT_NAME: wait/io/file/innodb/innodb_data_file
COUNT_READ: 9370680
SUM_NUMBER_OF_BYTES_READ: 153529188352
COUNT_WRITE: 67576376
SUM_NUMBER_OF_BYTES_WRITE: 1107815432192
8，哪个索引使用最多：
zjy@performance_schema 12:18:42>SELECT OBJECT_NAME, INDEX_NAME, COUNT_FETCH, COUNT_INSERT, COUNT_UPDATE, COUNT_DELETE FROM table_io_waits_summary_by_index_usage ORDER BY SUM_TIMER_WAIT DESC limit 1;
+-------------+------------+-------------+--------------+--------------+--------------+
| OBJECT_NAME | INDEX_NAME | COUNT_FETCH | COUNT_INSERT | COUNT_UPDATE | COUNT_DELETE |
+-------------+------------+-------------+--------------+--------------+--------------+
| fans | PRIMARY | 29002695158 | 0 | 296373434 | 0 |
+-------------+------------+-------------+--------------+--------------+--------------+
1 row in set (0.29 sec)
通过table_io_waits_summary_by_index_usage表，可以获得系统运行到现在，哪个表的具体哪个索引(包括主键索引，二级索引)使用最多。
9，哪个索引没有使用过：
zjy@performance_schema 12:23:22>SELECT OBJECT_SCHEMA, OBJECT_NAME, INDEX_NAME FROM table_io_waits_summary_by_index_usage WHERE INDEX_NAME IS NOT NULL AND COUNT_STAR = 0 AND OBJECT_SCHEMA <> \'mysql\' ORDER BY OBJECT_SCHEMA,OBJECT_NAME;
10，哪个等待事件消耗的时间最多：
zjy@performance_schema 12:25:22>SELECT EVENT_NAME, COUNT_STAR, SUM_TIMER_WAIT, AVG_TIMER_WAIT FROM events_waits_summary_global_by_event_name WHERE event_name != \'idle\' ORDER BY SUM_TIMER_WAIT DESC LIMIT 1;
11，类似profiling功能：
分析具体某条SQL，该SQL在执行各个阶段的时间消耗，通过events_statements_xxx表和events_stages_xxx表，就可以达到目的。两个表通过event_id与nesting_event_id关联，stages表的nesting_event_id为对应statements表的event_id；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，通过stage_xxx表的event_id字段与waits_xxx表的nesting_event_id进行关联。如：
View Code总结：
本文通过对Performance Schema数据库的介绍，主要用于收集数据库服务器性能参数：①提供进程等待的详细信息，包括锁、互斥变量、文件信息；②保存历史的事件汇总信息，为提供MySQL服务器性能做出详细的判断；③对于新增和删除监控事件点都非常容易，并可以改变mysql服务器的监控周期，例如（CYCLE、MICROSECOND）。通过该库得到数据库运行的统计信息，更好分析定位问题和完善监控信息。类似的监控还有：
打开标准的innodb监控：
CREATE TABLE innodb_monitor (a INT) ENGINE=INNODB;
打开innodb的锁监控：
CREATE TABLE innodb_lock_monitor (a INT) ENGINE=INNODB;
打开innodb表空间监控：
CREATE TABLE innodb_tablespace_monitor (a INT) ENGINE=INNODB;
打开innodb表监控：
CREATE TABLE innodb_table_monitor (a INT) ENGINE=INNODB;
参考文章：
https://dev.mysql.com/doc/refman/5.6/en/performance-schema.html
http://www.cnblogs.com/cchust/p/5022148.html
http://www.cnblogs.com/cchust/p/5057498.html
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