MySQL Explain 详解
24 June, 2017
本周五做的一次关于 MySQL explain 的技术分享。
PPT
大纲
Objective
- give you the hunch: bad query? best query?
- which columns are most important?
Material and Method
- MySQL 5.7.17
- Sakila sample database
Questions
- Shall we add indexes?
- Are indexes efficient?
- What’s executation plan of optimizer?
- How to optimize queries?
what does those mean?
- id
- select_type
- table
- access_type
- ref
- rows
- extra
Which columns are more important?
- access type
- rows
- extra
录像
视频存放在一个叫 Youtube 的不存在的网站上