Re: Optimizer questions

I wrote:
> BTW, there's some additional refactoring I had had in mind to do in
> grouping_planner to make its handling of the targetlist a bit more
> organized; in particular, I'd like to see it using PathTarget
> representation more consistently throughout the post-scan-join steps.

See 51c0f63e4d76a86b44e87876a6addcfffb01ec28 --- I think this gets
things to where we could plug in additional levels of targets without
too much complication.
        regards, tom lane