1. show variables like '%profiling%';(查看profiling信息)
2. set profiling=1;（开启profiling）
3. 执行SQL查询
例:select goods_name from ecs_goods where goods_id <5000;
show profiles;
4. show profile for query 4;
show profile 的格式如下：
SHOW PROFILE [type [, type] ... ]
[FOR QUERY n]
[LIMIT row_count [OFFSET offset]]
type:
ALL
| BLOCK IO
| CONTEXT SWITCHES
| CPU
| IPC
| MEMORY
| PAGE FAULTS
| SOURCE
| SWAPS
