Re: WIP: Upper planner pathification

Robert Haas <robertmhaas@gmail.com> writes:
> On Mon, Mar 14, 2016 at 9:21 PM, Kouhei Kaigai <kaigai@ak.jp.nec.com> wrote:
>> So, even though we don't need to define multiple hook declarations,
>> I think the hook invocation is needed just after create_xxxx_paths()
>> for each. It will need to inform extension the context of hook
>> invocation, the argument list will take UpperRelationKind.

> That actually seems like a pretty good point.  Otherwise you can't
> push anything from the upper rels down unless you are prepared to
> handle all of it.

I'm not exactly convinced of the use-case for that.  What external
thing is likely to handle window functions but not aggregation,
for example?
        regards, tom lane