Martijn van Oosterhout <kleptog@svana.org> writes:
> However, I don't know it matters. You only need to cost the plan if
> there are alternate paths and given the plan structure is strongly
> constrained, I'm not sure how much it matters.
It does, since the whole thing could be a subquery, in which case there
could be options available at the outer level. I doubt we'll be able to
be really smart, but that doesn't mean we can just punt.
> In the case of read-committed mode, will two seq-scans always
> return the same result?
They definitely should, since we'll be using the same snapshot
throughout the query.
regards, tom lane