查看事务等待状况
select
r.trx_id waiting_trx_id,
r.trx_mysql_thread_id waiting_thread,
r.trx_query waiting_query,
b.trx_id blocking_trx_id,
b.trx_mysql_thread_id blocking_thread,
b.trx_query blocking_query
from
information_schema.innodb_lock_waits w
inner join information_schema.innodb_trx b on b.trx_id = w.blocking_trx_id
inner join information_schema.innodb_trx r on r.trx_id = w.requesting_trx_id;
查看更具体的事务等待状况
select
b.trx_state,
e.state,
e.time,
d.state as block_state,
d.time as block_time,
a.requesting_trx_id,
a.requested_lock_id,
b.trx_query,
b.trx_mysql_thread_id,
a.blocking_trx_id,
a.blocking_lock_id,
c.trx_query as block_trx_query,
c.trx_mysql_thread_id as block_trx_mysql_tread_id
from
information_schema.innodb_lock_waits a
left join information_schema.innodb_trx b on a.requesting_trx_id = b.trx_id
left join information_schema.innodb_trx c on a.blocking_trx_id = c.trx_id
left join information_schema.processlist d on c.trx_mysql_thread_id = d.id
left join information_schema.processlist e on b.trx_mysql_thread_id = e.id
order by
a.requesting_trx_id;
查看未关闭的事务
mysql 5.5/mysql5.7
select
a.trx_id,
a.trx_state,
a.trx_started,
a.trx_query,
b.id,
b. user,
b. host,
b.db,
b.command,
b.time,
b.state,
b.info
from
information_schema.innodb_trx a
left join information_schema.processlist b on a.trx_mysql_thread_id = b.id
where
b.command = 'sleep';
mysql 5.6
select
a.trx_id,
a.trx_state,
a.trx_started,
a.trx_query,
b.id,
b.user,
b.db,
b.command,
b.time,
b.state,
b.info,
c.processlist_user,
c.processlist_host,
c.processlist_db,
d.sql_text
from
information_schema.innodb_trx a
left join information_schema.processlist b on a.trx_mysql_thread_id = b.id
and b.command = 'sleep'
left join performance_schema.threads c on b.id = c.processlist_id
left join performance_schema.events_statements_current d on d.thread_id = c.thread_id;
未关闭事务信息
select
t1.trx_id,
t1.trx_started,
t1.trx_mysql_thread_id,
t3.event_id,
t3.end_event_id,
t3.sql_text,
concat('mysql --login-path=3306 -e ''kill ',t1.trx_mysql_thread_id,'''')
from
information_schema.innodb_trx t1
left join `performance_schema`.threads t2
on t1.trx_mysql_thread_id=t2.processlist_id
left join `performance_schema`.events_statements_history t3
on t2.thread_id=t3.thread_id
where
t1.trx_started < date_sub(now(), interval 1 minute)
and t1.trx_operation_state is null
and t1.trx_query is null
order by event_id desc
查看某段时间以来未关闭事务
select
trx_id,
trx_started,
trx_mysql_thread_id
from
information_schema.innodb_trx
where
trx_started < date_sub(now(), interval 1 minute)
and trx_operation_state is null
and trx_query is null;
最后一次执行的sql语句，可以用于查询未结束的事务
select
*
from
`performance_schema`.events_statements_current
where
thread_id in (
select
thread_id
from
`performance_schema`.threads
where
processlist_id = 108
)
查看历史会话
select
*
from
`performance_schema`.events_statements_history
where
thread_id in (
select
thread_id
from
`performance_schema`.threads
where
processlist_id = 84
)
查看哪些用户占用了大量的资源
mysql> select * from user_summary\g
*************************** 1. row ***************************
user: root
statements: 3331 //用户执行的sql语句总数量
statement_latency: 2.86 s //该用户执行sql总的等待时间，即累计的sql执行时间
statement_avg_latency: 857.30 us //单次sql的平均执行时间
table_scans: 67 //全表扫描次数
file_ios: 23626 //io次数
file_io_latency: 1.72 s //io消耗的总时间
current_connections: 1 //该用户的当前连接会话数
total_connections: 9 //该用户连接会话总数
unique_hosts: 1 //用户发起的连接中唯一主机的数量，即从几个主机发起过数据库连接
current_memory: 0 bytes //当前被分配的内存
total_memory_allocated: 0 bytes //总共被分配的内存
*************************** 2. row ***************************
user: background
statements: 0
statement_latency: 0 ps
statement_avg_latency: 0 ps
table_scans: 0
file_ios: 2127
file_io_latency: 161.74 ms
current_connections: 26
total_connections: 30
unique_hosts: 0
current_memory: 0 bytes
total_memory_allocated: 0 bytes
2 rows in set (0.02 sec)
通过上述查询，可以简单看到每个用户占用的连接、内存、io等资源
如果想要进一步查询某项指标的话，可以查看对应的视图
查看哪些用户占用的详细指标
mysql> show tables like 'user%';
+-----------------------------------+
| tables_in_sys (user%) |
+-----------------------------------+
| user_summary |
| user_summary_by_file_io |
| user_summary_by_file_io_type |
| user_summary_by_stages |
| user_summary_by_statement_latency |
| user_summary_by_statement_type
mysql> select * from user_summary_by_statement_latency\g
这个视图概述了每个用户执行sql的大体统计信息，本人简单分析如下：
user 用户名
total 该用户总共执行的sql语句的数量
total_latency 执行sql总共的等待时间
max_latency 单次执行的最长等待时间
lock_latency 锁等待累计时间
rows_sent 该用户执行sql累积返回的行数
rows_examined 未执行用户sql存储引擎读取的总行数
rows_affected 被用户sql语句影响的总行数
full_scans 该用户执行的sql中造成全表扫描的总次数
如果想了解各个用户占用的io带宽，可查询如下视图
mysql> select * from user_summary_by_file_io\g
*************************** 1. row ***************************
user: root
ios: 23655
io_latency: 1.72 s
*************************** 2. row ***************************
user: background
ios: 2144
io_latency: 162.43 ms
2 rows in set (0.01 sec)
这个视图相对比较简单，列举的是每个用户下的io事件次数，以及io等待的累计时间
除此之外，我们还可以根据waits_by_user_by_latency视图查看每个用户的等待事件
mysql> desc waits_by_user_by_latency;
通过sys schema查询innodb的锁信息
innodb_lock_waits
mysql 5.7.7开始，sys schema中提供了innodb_lock_waits视图，通过这个视图，我们可以更直观清晰地查看当前事务间的阻塞关系。在此列举几个受关注的列，如下：
waiting_trx_id 等待事务的id
waiting_trx_age 等待的时间
waiting_query 等待锁资源的sql
waiting_lock_mode 请求锁的模式
blocking_trx_id 阻塞事务的id
blocking_trx_age 阻塞事务被执行的时间
blocking_query 阻塞事务正在执行的sql
blocking_lock_mode 阻塞的锁模式
locked_table 被加锁的表
locked_index 被加锁的索引
schema_table_lock_waits
5.7.9中新增的视图，通过这个视图可以查询阻塞会话的metadata lock信息
解除正在死锁的状态有两种方法：
第一种：
1.查询是否锁表
show open tables where in_use > 0;
2.查询进程（如果您有super权限，您可以看到所有线程。否则，您只能看到您自己的线程）
show processlist
3.杀死进程id（就是上面命令的id列）
kill id
第二种：
1.查看下在锁的事务
select * from information_schema.innodb_trx;
2.杀死进程id（就是上面命令的trx_mysql_thread_id列）
kill 线程id
例子：
查出死锁进程：show processlist
杀掉进程 kill 420821;
其它关于查看死锁的命令：
1：查看当前的事务
select * from information_schema.innodb_trx;
2：查看当前锁定的事务
select * from information_schema.innodb_locks;
3：查看当前等锁的事务
select * from information_schema.innodb_lock_waits;
