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
以下是引用片段：
<p> mysql> status; <br>-------------- <br>mysql Ver 11.18 Distrib 3.23.58, for redhat-linux-gnu (i386) <br>Connection id: 53 <br>Current database: (null) <br>Current user: root@localhost <br>Current pager: stdout <br>Using outfile: '' <br>Server version: 5.0.37-log <br>Protocol version: 10 <br>Connection: Localhost via UNIX socket <br>Client characterset: latin1 <br>Server characterset: latin1 <br>UNIX socket: /tmp/mysql.sock <br>Uptime: 4 days 16 hours 49 min 57 sec <br>Threads: 1 Questions: 706 Slow queries: 0 Opens: 177 Flush tables: 1 Open tables:</p><p>52 Queries per second avg: 0.002 <br>-------------- </p> 登入後複製 |
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 |
+----+------+-----------+------+---------+------+-------+------------------+
