概念：

MySQL执行计划（Execution Plan）是数据库系统根据查询语句生成的一种执行策略，用于指导数据库引擎执行查询操作。

English Unit

This chapter explains how to optimize MySQL performance and provides examples. Optimization involves configuring, tuning, and measuring performance, at several levels. Depending on your job role (developer, DBA, or a combination of both), you might optimize at the level of individual SQL statements, entire applications, a single database server, or multiple networked database servers. Someti