MySQL query timing out: (70100): Query execution was interrupted

Question

I want to execute a MySQL query in order to delete all Wp_posts table rows which post_parent is a Wp_posts row with post_type

Answer 1

Some versions of MySQL implement in with a subquery in a very inefficient manner. Change it to a correlated exists clause:

DELETE FROM wp_posts
    WHERE exists (SELECT 1 FROM temp where temp.tid = wp_posts.post_parent)