mysql的sql语句优化都使用explain，但是这个没有办法知道详细的Memory/CPU等使用量
MySQL Query Profiler, 可以查询到此 SQL 语句会执行多少, 并看出 CPU/Memory 使用
量, 执行过程 System lock, Table lock 花多少时间等等.
mysql> show variables like 'profiling%';
+------------------------+-------+
| Variable_name | Value |
+------------------------+-------+
| profiling | OFF |
| profiling_history_size | 15 |
+------------------------+-------+
开启此功能
mysql>set profiling=1;
mysql> show variables like 'profiling%';
# 此命令会让mysql在 information_schema 的 database 建立一個 PROFILING 的
table 来记录.
+------------------------+-------+
| Variable_name | Value |
+------------------------+-------+
| profiling | ON |
| profiling_history_size | 15 |
+------------------------+-------+
profiling_history_size记录多少次查询
mysql> show profiles;
+----------+------------+------------------------------------+
| Query_ID | Duration | Query |
+----------+------------+------------------------------------+
| 1 | 0.00018100 | show variables like 'profiling%' |
| 2 | 0.00020400 | show variables like 'profiling%' |
| 3 | 0.00007800 | set profiling=1 |
| 4 | 0.00011000 | show variables like 'profiling%' |
| 5 | 0.00002400 | select count(1) from `mrhao_stats` |
| 6 | 1.52181400 | select count(*) from `mrhao_stats` |
| 7 | 0.00026900 | show variables like 'profiling%' |
mysql> show profile for query 6;
+--------------------------------+----------+
| Status | Duration |
+--------------------------------+----------+
| (initialization) | 0.000003 |
| checking query cache for query | 0.000042 |
| Opening tables | 0.00001 |
| System lock | 0.000004 |
| Table lock | 0.000025 |
| init | 0.000009 |
| optimizing | 0.000003 |
| statistics | 0.000007 |
| preparing | 0.000007 |
| executing | 0.000004 |
| Sending data | 1.521676 |
| end | 0.000007 |
| query end | 0.000003 |
| storing result in query cache | 0.000002 |
| freeing items | 0.000006 |
| closing tables | 0.000004 |
| logging slow query | 0.000002 |
+--------------------------------+----------+
17 rows in set (0.00 sec)
mysql> show profile cpu for query 6;
+--------------------------------+----------+----------+------------+
| Status | Duration | CPU_user | CPU_system |
+--------------------------------+----------+----------+------------+
| (initialization) | 0.000003 | 0 | 0 |
| checking query cache for query | 0.000042 | 0.001 | 0 |
| Opening tables | 0.00001 | 0 | 0 |
| System lock | 0.000004 | 0 | 0 |
| Table lock | 0.000025 | 0 | 0 |
| init | 0.000009 | 0 | 0 |
| optimizing | 0.000003 | 0 | 0 |
| statistics | 0.000007 | 0 | 0 |
| preparing | 0.000007 | 0 | 0 |
| executing | 0.000004 | 0 | 0 |
| Sending data | 1.521676 | 1.631752 | 0.036995 |
| end | 0.000007 | 0 | 0 |
| query end | 0.000003 | 0 | 0 |
| storing result in query cache | 0.000002 | 0 | 0 |
| freeing items | 0.000006 | 0 | 0 |
| closing tables | 0.000004 | 0 | 0 |
| logging slow query | 0.000002 | 0 | 0 |
+--------------------------------+----------+----------+------------+
17 rows in set (0.00 sec)
* ALL - displays all information
* BLOCK IO - displays counts for block input and output operations
* CONTEXT SWITCHES - displays counts for voluntary and involuntary
context switches
* IPC - displays counts for messages sent and received
* MEMORY - is not currently implemented
* PAGE FAULTS - displays counts for major and minor page faults
* SOURCE - displays the names of functions from the source code, together
with the name and line number of the file in which the function occurs
* SWAPS - displays swap counts
查询时间跟cpu的使用
mysql> select min(seq) seq,state,count(*) numb_ops,
round(sum(duration),5) sum_dur, round(avg(duration),5) avg_dur,
round(sum(cpu_user),5) sum_cpu, round(avg(cpu_user),5) avg_cpu
from information_schema.profiling
where query_id = 7
group by state
order by seq;
关闭此功能
mysql> set profiling=0;
mysql> show variables like 'profiling%';
+------------------------+-------+
| Variable_name | Value |
+------------------------+-------+
| profiling | OFF |
| profiling_history_size | 15 |
+------------------------+-------+
