Re: make Gather node projection-capable

Robert Haas <robertmhaas@gmail.com> writes:
> The Gather node, as currently committed, is neither projection-capable
> nor listed as an exception in is_projection_capable_plan.  Amit
> discovered this in testing, and I hit it in my testing as well.  We
> could just mark it as being not projection-capable, but I think it
> might be better to go the other way and give it projection
> capabilities.

Um ... why would you not want the projections to happen in the child
nodes, where they could be parallelized?  Or am I missing something?

> While that's not the end of the world, it seems to needlessly fly in
> the face of the general principle that nodes should generally try to
> support projection.

I'm not sure there is any such principle.
        regards, tom lane