Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> writes:
> Arne complained that there should be a unique constraint on (tgrelid,
> tgparentid) which would sidestep the need for this to be a loop. I
> don't think it's really necessary, and I'm not sure how to create a
> system index WHERE tgparentid <> 0.
Yeah, we don't support partial indexes on catalogs, and this example
doesn't make me feel like we ought to open that can of worms. But
then maybe this function shouldn't assume there's only one match?
regards, tom lane