Speaker Deck

Understanding MySQL Explain

by Ryan Lv

Published June 24, 2017 in Technology

## 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

视频

https://www.youtube.com/edit?o=U&video_id=3U-qFPlCLlM

PPT

https://speakerdeck.com/xiaoronglv/understanding-mysql-explain

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