Re: [v9.5] Custom Plan API

> On Wed, May 7, 2014 at 4:01 AM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
> > Agreed. My proposal is that if the planner allows the lookaside to an
> > FDW then we pass the query for full execution on the FDW. That means
> > that the scan, aggregate and join could take place via the FDW. i.e.
> > "Custom Plan" == lookaside + FDW
> >
> > Or put another way, if we add Lookaside then we can just plug in the
> > pgstrom FDW directly and we're done. And everybody else's FDW will
> > work as well, so Citus etcc will not need to recode.
>
> As Stephen notes downthread, Tom has already expressed opposition to this
> idea on other threads, and I tend to agree with him, at least to some degree.
> I think the drive to use foreign data wrappers for PGStrom, CitusDB, and
> other things that aren't really foreign data wrappers as originally
> conceived is a result of the fact that we've got only one interface in this
> area that looks remotely like something pluggable; and so everyone's trying
> to fit things into the constraints of that interface whether it's actually
> a good fit or not.
> Unfortunately, I think what CitusDB really wants is pluggable storage, and
> what PGStrom really wants is custom paths, and I don't think either of those
> things is the same as what FDWs provide.
>
Yes, what PGStrom really needs is a custom paths; that allows extension to
replace a part of built-in nodes according to extension's characteristics.
The discussion upthread clarified that FDW needs to be enhanced to support
functionality that PGStrom wants to provide, however, some of them also needs
redefinition of FDW, indeed.

Umm... I'm now missing the direction towards my goal.
What approach is the best way to glue PostgreSQL and PGStrom?

Thanks,
--
NEC OSS Promotion Center / PG-Strom Project
KaiGai Kohei <kaigai(at)ak(dot)jp(dot)nec(dot)com>