Index design specification

(indexes can increase query efficiency, but also reduce the efficiency of inserts and updates.)

(so each innodb table must have a primary key.)

Because innodb is because of the index organization table, if the primary key is updated frequently, it means that the logical data stored in the data will change frequently, which will inevitably lead to a large number of io operations and cpu time, which will degrade performance, especially for large tables.

Uuid, md5, hash, and strings do not grow sequentially. When data is inserted in order to ensure the order of the index, sort insertion is carried out, which takes up a lot of cpu time and io operations. So columns that want to grow sequentially must not be empty as primary keys.

Which columns are indexed?

How do I choose the order of federated index columns?