How to interact with the server when the client sends an SQL message

3000 Million data has finally been put into storage , Let's look at the file structure ：

idb about 3.2G, About 100 minute  

1. validators ： in other words navicat The password you enter must match mysql The server background verifies

2. Lexical parser ： Like the following sql, That is, check sql Legitimacy  

3. Optimizer ：

Look at this sql, Why? name Obviously 74, Actually 4 Well ？

because mysql The optimizer is optimized ： Changed the position , Go to the primary key index , So it is 4
explain  select * from employees where id=3  and name='zhuge2' 

4. actuator ： perform sql

5. Storage engine ： Mainly innodb

6. file system ：