1 Query Type
查询类型包含:
a full table scan , index scans, range scans, unique index lookups, and constants.
const Type: 主键查询一般为Const类型
All Type : 全表扫描
2 为啥要拆分JOIN操作
Caching can be more efficient;
Executing the queries individually can sometimes reduce lock contention;
Scale database more easily;
Reduce redundant row access;
3 Query states
MYSQL查询状态
show full processList ;
Sleep ,
Query,
Sorting result,
Sending data,
Locked,
Analyzing and statistics
4 SHOW STATUS
查看MYSQL状态信息
5 让MYSQL不走缓冲
SELECT SQL_NO_CACHE COUNT(*) FROM XXX
MYSQL查询流程图
链接 http://my.oschina.net/robinyao/blog/530180
时间: 2024-08-01 22:29:47