Re: Optimization for updating foreign tables in Postgres FDW

On 2015/05/13 0:55, Stephen Frost wrote:
> Etsuro,
>
> * Etsuro Fujita (fujita(dot)etsuro(at)lab(dot)ntt(dot)co(dot)jp) wrote:
>> Here is an updated version. In this version, the bug has been
>> fixed, but any regression tests for that hasn't been added, because
>> I'm not sure that the above way is a good idea and don't have any
>> other ideas.
>>
>> The EXPLAIN output has also been improved as discussed in [1].
>
> While the EXPLAIN output changed, the structure hasn't really changed
> from what was discussed previously and there's not been any real
> involvment from the core code in what's happening here.
>
> Clearly, the documentation around how to use the FDW API hasn't changed
> at all and there's been no additions to it for handling bulk work.
> Everything here continues to be done inside of postgres_fdw, which
> essentially ignores the prescribed "Update/Delete one tuple" interface
> for ExecForeignUpdate/ExecForeignDelete.
>
> I've spent the better part of the past two days trying to reason my way
> around that while reviewing this patch and I haven't come out the other
> side any happier with this approach than I was back in
> 20140911153049(dot)GC16422(at)tamriel(dot)snowman(dot)net(dot)
>
> There are other things that don't look right to me, such as what's going
> on at the bottom of push_update_down(), but I don't think there's much
> point going into it until we figure out what the core FDW API here
> should look like. It might not be all that far from what we have now,
> but I don't think we can just ignore the existing, documented, API.

OK, I'll try to introduce the core FDW API for this (and make changes to
the core code) to address your previous comments.

Thanks for taking the time to review the patch!

Best regards,
Etsuro Fujita