Alan Hodgson <ahodgson(at)simkin(dot)ca> writes:
> Do you have other foreign keys into supplierProduct on other tables where
> the relevant columns aren't indexed? Slow deletes are usually caused by
> that.
Yeah. The query plan itself looks perfectly reasonable, so I'm
suspecting the problem is something happening subsequent to the row
deletions --- like foreign key constraint checking.
regards, tom lane