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mysql中查询联接工作状态

www.MyException.Cn  网友分享于:2018-06-08  浏览:0次
mysql中查询连接工作状态
#!/bin/bash
while true
do
mysql -uroot -e 'show processlist\G'|grep State:|uniq -c|sort -rn
echo '---'
sleep 1
Done


如果观察到以下状态,则需要注意
converting HEAP to MyISAM 查询结果太大时,把结果放在磁盘 (语句写的不好,取数据太多)
create tmp table             创建临时表(如group时储存中间结果,说明索引建的不好)
Copying to tmp table on disk   把内存临时表复制到磁盘 (索引不好,表字段选的不好)
locked         被其他查询锁住 (一般在使用事务时易发生,互联网应用不常发生)
logging slow query 记录慢查询
mysql 5.5 以后加了一个profile设置,可以观察到具体语句的执行步骤.
0:查看profile是否开启

> Show  variables like ‘profiling’
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| profiling     | OFF   |
+---------------+-------+

1:> set profiling=on;
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| profiling     | On      |
+---------------+-------+


mysql> show profiles;
+----------+------------+----------------------------------------------------------+
| Query_ID | Duration   | Query                                                    |
+----------+------------+----------------------------------------------------------+
|        1 | 0.00034225 | select cat_id,avg(shop_price) from goods group by cat_id |
+----------+------------+----------------------------------------------------------+
1 row in set (0.00 sec)

mysql> show profile for query 1;
+----------------------+----------+
| Status               | Duration |
+----------------------+----------+
| starting             | 0.000058 |
| checking permissions | 0.000008 |
...
...
| Sorting result       | 0.000004 |
| Sending data         | 0.000120 |
| end                  | 0.000005 |
| query end            | 0.000006 |
| closing tables       | 0.000008 |
| freeing items        | 0.000023 |
| logging slow query   | 0.000003 |
| cleaning up          | 0.000004 |
+----------------------+----------+

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