ORDER BY NULL in MySQL

Question

What is ORDER BY NULL in MySQL?

Does it decrease the query speed?

Answer 1

Since Mysql 8.0 ORDER BY NULL doesn't improve query performance.

https://dev.mysql.com/doc/refman/8.0/en/order-by-optimization.html

Previously (MySQL 5.7 and lower), GROUP BY sorted implicitly under certain conditions. In MySQL 8.0, that no longer occurs, so specifying ORDER BY NULL at the end to suppress implicit sorting (as was done previously) is no longer necessary. However, query results may differ from previous MySQL versions. To produce a given sort order, provide an ORDER BY clause.