mysql创建索引来查询不进入数据表查询的吗

Question

求大神讲下原理

Answer 1

First of all, the index is a data structure that is stored on the disk in the form of a file, so the queries that can use the index are mainly disk I/O operations

Approximate process: first analyze the SQL statement, if the index can be used, read the disk according to the algorithm, obtain the final query result, and return it

You can learn more about the commonly used data structure algorithms: B-Tree

I said I don’t understand that deeply