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

From: Andres Freund <andres(at)anarazel(dot)de>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Dilip Kumar <dilipbalaut(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Proposal: scan key push down to heap [WIP]
Date: 2016-10-31 16:13:11
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On 2016-10-31 09:28:00 -0400, Robert Haas wrote:
> On Fri, Oct 28, 2016 at 2:46 AM, Andres Freund <andres(at)anarazel(dot)de> wrote:
> > Well, that'll also make the feature not particularly useful :(. My
> > suspicion is that the way to suceed here isn't to rely more on testing
> > as part of the scan, but create a more general fastpath for qual
> > evaluation, which atm is a *LOT* more heavyweight than what
> > HeapKeyTest() does. But maybe I'm biased since I'm working on the
> > latter...
> I think you might be right, but I'm not very clear on what the
> timeline for your work is.

Me neither. But I think if we can stomach Dilip's approach of using a
slot in heapam, then I think my concerns are addressed, and this is
probably going go to be a win regardless of faster expression evaluation
and/or batching.

> It would be easier to say, sure, let's put
> this on hold if we knew that in a month or two we could come back and
> retest after you've made some progress. But I don't know whether
> we're talking about months or years.

I sure hope it's months.


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