Greg Stark <gsstark@mit.edu> writes:
> I wouldn't expect it to actually take any more time. In fact I would expect it
> to take a lot less time since it takes time to handle the resulting data too.
You're mistaking planner estimate time for reality ;-).
IIRC, the planner doesn't bother to account for evaluation time of
select-list values in its estimates. At least in simple cases, there's
no point in doing that math because the cost will be the same no matter
what plan is chosen.
regards, tom lane