I've solved it. I just used a subselect. Worked very quickly. I had a lot of trouble with subqueries when I first started databases with MySQL. So I have been afraid of them.
update entities set customer_status = select(customer_status from entity_dimension_update where entities.entity_id = entity_dimension_update.entity_id); Worked almost instantly. My apologies for the spam. -- matthew.pugs...@gmail.com