Re: What is the extent of FDW join pushdown support in 9.5?

On Wed, Sep 16, 2015 at 04:32:51PM -0400, Peter Eisentraut wrote:
> On 9/15/15 10:02 PM, Kouhei Kaigai wrote:
> >> The 9.5 release notes contain this promising but cryptic item:
> >>
> >> - Allow foreign data wrappers and custom scans to implement join
> >> pushdown (KaiGai Kohei)
> >>
> >> As phrased, this seems to mean, "it can be done, but we haven't done
> >> it". But there is no link to any documentation that explains how to do
> >> this. The commit that appears to have added this feature touches
> >> postgres_fdw, but neither the documentation nor the tests show anything
> >> about this feature, and I haven't been able to reproduce anything that
> >> would seem to indicate anything like this is at work.
> >>
> >> So what is the actual extent of this feature?
> >>
> > It says these enhancement on interface allows extensions to implement
> > join operation in their own way (including remote join in case of FDW),
> > however, enhancement of postgres_fdw is not yet upstreamed.
>
> Thank you for this clarification. I suppose this item is correct as
> written.

Yes, it was cryptically written on purpose. ;-)

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