Re: Foreign join pushdown vs EvalPlanQual

On Tue, Dec 8, 2015 at 10:00 PM, Etsuro Fujita
<fujita(dot)etsuro(at)lab(dot)ntt(dot)co(dot)jp> wrote:
>> I think the actual regression test outputs are fine, and that your
>> desire to suppress part of the plan tree from showing up in the
>> EXPLAIN output is misguided. I like it just the way it is. To
>> prevent user confusion, I think that when we add support to
>> postgres_fdw for this we might also want to add some documentation
>> explaining how to interpret this EXPLAIN output, but I don't think
>> there's any problem with the output itself.
>
> I'm not sure that that's a good idea. one reason for that is I think that
> that would be more confusing to users when more than two foreign tables are
> involved in a foreign join as shown in the following example. Note that the
> outer plans will be shown recursively. Another reason is there is no
> consistency between the costs of the outer plans and that of the main plan.

I still don't really see a problem here, but, regardless, the solution
can't be to hide nodes that are in fact present from the user. We can
talk about making further changes here, but hiding the nodes
altogether is categorically out in my mind.

--
Robert Haas
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