Re: Properly pathify the union planner

On Wed, Mar 27, 2024 at 6:34 PM David Rowley <dgrowleyml(at)gmail(dot)com> wrote:

> On Wed, 27 Mar 2024 at 22:47, David Rowley <dgrowleyml(at)gmail(dot)com> wrote:
> > I did wonder when first working on this patch if subquery_planner()
> > should grow an extra parameter, or maybe consolidate some existing
> > ones by passing some struct that provides the planner with a bit more
> > context about the query. A few of the existing parameters are likely
> > candidates for being in such a struct. e.g. hasRecursion and
> > tuple_fraction. A SetOperationStmt could go in there too.
>
> The attached is roughly what I had in mind. I've not taken the time
> to see what comments need to be updated, so the attached aims only to
> assist discussion.

I like this idea. And there may be future applications for having such
a struct if we want to pass down additional information to subquery
planning, such as ordering requirements from outer query.

Thanks
Richard