Re: Optimization for updating foreign tables in Postgres FDW

Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Wed, Mar 9, 2016 at 1:12 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> I hadn't been paying any attention to this thread, but I wonder whether
>> this entire approach isn't considerably inferior to what we can do now
>> with the planner pathification patch. To quote from the new docs:

> Well, I guess I'm not quite seeing it. What do you have in mind?
> Just taking a guess here, you might be thinking that instead of
> something like this...

> Update on public.ft2
> -> Foreign Update on public.ft2

> We could boil it all the way down to this:

> Foreign Update on public.ft2

Exactly. I'm not claiming that that would be particularly faster, but
it would eliminate a whole bunch of seriously ugly stuff that's in
this patch.

> But can you, really? What if the UPDATE is targeting an inheritance
> hierarchy containing some local tables and some remote tables?

I don't really see why that couldn't be made to work. You'd end up
with ForeignUpdates on the remote tables and a ModifyTable handling
the rest.

regards, tom lane