Mysql查看连接数相关信息

MySQL查看连接数相关信息在

数据库：INFORMATION_SCHEMA
表：PROCESSLIST

表结构如下：

mysql> desc PROCESSLIST;
+---------+-------------+------+-----+---------+-------+
| Field   | Type        | Null | Key | Default | Extra |
+---------+-------------+------+-----+---------+-------+
| ID      | bigint()   | NO   |     |        |       |
| USER    | varchar() | NO   |     |         |       |
| HOST    | varchar() | NO   |     |         |       |
| DB      | varchar() | YES  |     | NULL    |       |
| COMMAND | varchar() | NO   |     |         |       |
| TIME    | int()      | NO   |     |        |       |
| STATE   | varchar() | YES  |     | NULL    |       |
| INFO    | longtext    | YES  |     | NULL    |       |
+---------+-------------+------+-----+---------+-------+
 rows in set (0.00 sec)

查看单个host连接数：

select substring_index(host,":",1) ,count(1) as cnt
from INFORMATION_SCHEMA.PROCESSLIST
group by substring_index(host,":",1)
order by cnt desc 

查看db连接数：

select db,count() as cnt from INFORMATION_SCHEMA.PROCESSLIST group by db order by cnt desc;