MySQL中怎样行使profile说明SQL执行状态
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打开profile mysql> select @@have_profiling; +------------------+ | @@have_profiling | +------------------+ | YES | +------------------+ 1 row in set (0.00 sec) mysql> select @@profiling; +-------------+ | @@profiling | +-------------+ | 0 | +-------------+ 1 row in set (0.00 sec) mysql> set session profiling=1; Query OK, 0 rows affected (0.00 sec) mysql> select @@profiling; +-------------+ | @@profiling | +-------------+ | 1 | +-------------+ 1 row in set (0.00 sec) 使用profile分析SQL，可以看到执行两次后,Send data和sending cached result to clien执行效率的变化 mysql> select count(*) from sakila.payment; +----------+ | count(*) | +----------+ | 16049 | +----------+ 1 row in set (0.03 sec) mysql> show profiles; +----------+------------+-------------------------------------+ | Query_ID | Duration | Query | +----------+------------+-------------------------------------+ | 1 | 0.00020400 | select @@profiling | | 2 | 0.00008900 | select count(*) from payment | | 3 | 0.00006800 | show databaes | | 4 | 0.02102800 | show databases | | 5 | 0.02847600 | select count(*) from sakila.payment | 本栏目更多精彩内容：http://www.bianceng.cn/database/MySQL/ +----------+------------+-------------------------------------+ 5 rows in set (0.00 sec) mysql> show profile for query 5; +--------------------------------+----------+ | Status | Duration | +--------------------------------+----------+ | starting | 0.000030 | | Waiting for query cache lock | 0.000005 | | checking query cache for query | 0.000043 | | checking permissions | 0.000007 | | Opening tables | 0.000027 | | System lock | 0.000010 | | Waiting for query cache lock | 0.000010 | | init | 0.000000 | | optimizing | 0.023255 | | statistics | 0.000118 | | preparing | 0.000041 | | executing | 0.000033 | | Sending data | 0.003833 | | end | 0.000054 | | query end | 0.000045 | | closing tables | 0.000045 | | freeing items | 0.000072 | | Waiting for query cache lock | 0.000033 | | freeing items | 0.000785 | | Waiting for query cache lock | 0.000016 | | freeing items | 0.000002 | | storing result in query cache | 0.000005 | | logging slow query | 0.000003 | | cleaning up | 0.000004 | +--------------------------------+----------+ 24 rows in set (0.00 sec) mysql> select count(*) from sakila.payment; +----------+ | count(*) | +----------+ | 16049 | +----------+ 1 row in set (0.00 sec) mysql> show profiles; +----------+------------+-------------------------------------+ | Query_ID | Duration | Query | +----------+------------+-------------------------------------+ | 1 | 0.00020400 | select @@profiling | | 2 | 0.00008900 | select count(*) from payment | | 3 | 0.00006800 | show databaes | | 4 | 0.02102800 | show databases | | 5 | 0.02847600 | select count(*) from sakila.payment | | 6 | 0.00006900 | select count(*) from sakila.payment | +----------+------------+-------------------------------------+ 6 rows in set (0.00 sec) mysql> show profile for query 6; +--------------------------------+----------+ | Status | Duration | +--------------------------------+----------+ | starting | 0.000029 | | Waiting for query cache lock | 0.000004 | | checking query cache for query | 0.000007 | | checking privileges on cached | 0.000004 | | checking permissions | 0.000008 | | sending cached result to clien | 0.000012 | | logging slow query | 0.000002 | | cleaning up | 0.000003 | +--------------------------------+----------+ 8 rows in set (0.00 sec) （编辑：济南站长网） 【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容! |
