MySQLSQL剖析(SQLprofile)(三)
timizing | 0.000012 | 0.87 | 1 | 0.0000120000 |
| query end | 0.000011 | 0.79 | 1 | 0.0000110000 |
| end | 0.000010 | 0.72 | 1 | 0.0000100000 |
| closing tables | 0.000010 | 0.72 | 1 | 0.0000100000 |
| executing | 0.000006 | 0.43 | 1 | 0.0000060000 |
+----------------------+----------+-------+-------+--------------+
--开启profiling后，我们可以通过show profile等方式查看，其实质是这些开销信息被记录到information_schema.profiling表
--如下面的查询，部分信息省略
profiling
root@localhost[information_schema]> select * from profiling limit 3,3\G;
*************************** 1. row ***************************
QUERY_ID: 1
SEQ: 5
STATE: init
DURATION: 0.000020
CPU_USER: 0.000000
CPU_SYSTEM: 0.000000
CONTEXT_VOLUNTARY: 0
CONTEXT_INVOLUNTARY: 0
BLOCK_OPS_IN: 0
BLOCK_OPS_OUT: 0
MESSAGES_SENT: 0
MESSAGES_RECEIVED: 0
PAGE_FAULTS_MAJOR: 0
PAGE_FAULTS_MINOR: 0
SWAPS: 0
SOURCE_FUNCTION:
mysql_prepare_select
SOURCE_FILE: sql_select.cc
SOURCE_LINE: 1050
--停止profile,可以设置profiling参数，或者在session退出之后,profiling会被自动关闭
root@localhost[sakila]> set profiling=off;
Query OK, 0 rows affected, 1 warning (0.00 sec)