EXPLAIN and Query Tuning

Part of the MySQL course

"This query is slow." You will hear that sentence for the rest of your career, and the tempting response is to start changing things: add an index here, rewrite the join, maybe it is the ORDER BY. Guessing is a poor way to tune a database, and it is unnecessary, because MySQL will simply tell you what it plans to do.

Open the terminal, connect as root (the password is easyenv, as in lesson 02), and give this lesson a fresh database of its own ...