Alessandro Gagliardi <alessandro@path.com> writes:
> Argh! I can't believe I forgot the "LEFT". That's embarrassing. Anyway, I
> was wondering if a WHERE NOT EXISTS clause would be better. I'm still new
> to those, so didn't want to try to offer that as a solution, but I gather
> it can be more efficient than a JOIN in some cases.
Given a reasonably recent PG version, it should be exactly the same ---
the planner will translate both of those into anti-joins.
regards, tom lane