How to read MySQL EXPLAINs

This post provides a detailed guide on how to interpret MySQL's `EXPLAIN` and `EXPLAIN ANALYZE` output. It explains the various columns and their significance, such as `SELECT_TYPE`, `rows`, `key_len`, and `extra`. It also introduces `EXPLAIN ANALYZE` as a tool that runs the query to provide actual execution costs alongside estimates. The post outlines the benefits and limitations of these tools and provides a breakdown of MySQL join types with performance indicators.