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吕小荣

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MySQL Explain 详解

Published on 2017-06-24

本周五做的一次关于 MySQL explain 的技术分享。

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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

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吕小荣 at 22:52
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