通过status命令，查看Slow queries这一项，如果值长时间>0,说明有查询执行时间过长

以下为引用的内容：

mysql> status;

--------------

mysql Ver 11.18 Distrib 3.23.58, for redhat-linux-gnu (i386)

Connection id: 53

Current database: (null)

Current user: root@localhost

Current pager: stdout

Using outfile: ''

Server version: 5.0.37-log

Protocol version: 10

Connection: Localhost via UNIX socket

Client characterset: latin1

Server characterset: latin1

UNIX socket: /tmp/mysql.sock

Uptime: 4 days 16 hours 49 min 57 sec

Threads: 1 Questions: 706 Slow queries: 0 Opens: 177 Flush tables: 1 Open tables:

52 Queries per second avg: 0.002

--------------

这时再通过show processlist命令来查看当前正在运行的SQL，从中找出运行慢的SQL语句，找到执行慢的语句后，再用explain命令查看这些语句的执行计划。

mysql> show processlist;

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

| Id | User | Host | db | Command | Time | State | Info |

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

| 53 | root | localhost | NULL | Query | 0 | NULL | show processlist |

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