How to Read a MySQL EXPLAIN Plan (WordPress Edition)

You've Got a Slow Query. Now What? You know your WordPress site has slow database queries. Maybe you spotted them in Query Monitor, or your hosting company sent you a warning. You've got a query that takes 3 seconds when it should take 30 milliseconds. The next step is EXPLAIN . It's MySQL's built-in tool for showing you exactly how it executes a query — and where it goes wrong. Most WordPress developers never use it. That's a shame, because it's the single most useful tool for database performance. Running EXPLAIN Take any SQL query and put EXPLAIN in front of it: EXPLAIN SELECT p . ID , p . post_title FROM wp_posts p JOIN wp_postmeta pm ON p . ID = pm . post_id WHERE pm . meta_key = '_price' AND pm . meta_value > 100 AND p . post_type = 'product' AND p . post_status = 'publish' ; MySQL returns a table with several columns. Here are the ones that matter: The Columns That Matter type — How MySQL Accesses the Table This is the most important column. From best to worst: Type Meaning Spee