Very slow delete on mysql base with subquery

Question

This mysql query is running for around 10 hours and has not finished. Something is horribly wrong.

Two tables (text and spam) are here. Spam stores the ids of spam e

Answer 1

Your choice of where id in (select ...) will always perform poorly.

Instead, use a normal join which will be very efficient:

DELETE `text` 
FROM spam
join `text` on `text`.old_id = spam.textid;

Notice selection from spam first, then joining to text, which will give the best performance.