Re: Proposal: scan key push down to heap [WIP]

On Fri, Dec 2, 2016 at 8:41 AM, Andres Freund <andres(at)anarazel(dot)de> wrote:

> On 2016-11-30 16:11:23 +0530, Dilip Kumar wrote:
> > On Tue, Nov 29, 2016 at 11:21 PM, Robert Haas <robertmhaas(at)gmail(dot)com>
> wrote:
> > > On Mon, Nov 28, 2016 at 11:17 PM, Dilip Kumar <dilipbalaut(at)gmail(dot)com>
> wrote:
> > >> Actually we want to call slot_getattr instead heap_getattr, because of
> > >> problem mentioned by Andres upthread and we also saw in test results.
> > >
> > > Ah, right.
> > >
> > >> Should we make a copy of HeapKeyTest lets say ExecKeyTest and keep it
> > >> under executor ?
> > >
> > > Sure.
> >
> > I have worked on the idea you suggested upthread. POC patch is
> > attached.
>
> Hm. I'm more than a bit doubful about this approach. Shouldn't we just
> *always* do this as part of expression evaluation, instead of
> special-casing for seqscans?
>
> I.e. during planning recognize that an OpExpr can be evaluated as a
> scankey and then emit different qual evaluation instructions? Because
> then the benefit can be everywhere, instead of just seqscans.
>
> I'll post my new expression evaluation stuff - which doesn't do this
> atm, but makes ExecQual faster in other ways - later this week. If we
> could get the planner (or parse-analysis?) to set an OpExpr flag that
> signals that the expression can be evaluated as a scankey, that'd be
> easy.
>
>
Moved to next CF with "waiting on author" status.

Regards,
Hari Babu
Fujitsu Australia