Horton

Re: Hybrid Hash/Nested Loop joins and caching results from subplans

Ibrar Ahmed <ibrar.ahmad@gmail.com>

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From: Ibrar Ahmed <ibrar.ahmad@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Andres Freund <andres@anarazel.de>, David Rowley <dgrowleyml@gmail.com>, Konstantin Knizhnik <k.knizhnik@postgrespro.ru>, Andy Fan <zhihui.fan1213@gmail.com>, Alvaro Herrera <alvherre@alvh.no-ip.org>, PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>
Date: 2021-03-04T11:15:51Z
Lists: pgsql-hackers 
On Tue, Feb 23, 2021 at 10:44 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:

> Andres Freund <andres@anarazel.de> writes:
> > We could add a wrapper node around "planner expressions" that stores
> > metadata about them during planning, without those properties leaking
> > over expressions used at other times. E.g. having
> > preprocess_expression() return a PlannerExpr that that points to the
> > expression as preprocess_expression returns it today. That'd make it
> > easy to cache information like volatility. But it also seems
> > prohibitively invasive :(.
>
> I doubt it's that bad.  We could cache such info in RestrictInfo
> for quals, or PathTarget for tlists, without much new notational
> overhead.  That doesn't cover everything the planner deals with
> of course, but it would cover enough that you'd be chasing pretty
> small returns to worry about more.
>
>                         regards, tom lane
>
>
>
This patch set no longer applies
http://cfbot.cputube.org/patch_32_2569.log

Can we get a rebase?

I am marking the patch "Waiting on Author"



-- 
Ibrar Ahmed

Commits

  1. Add Result Cache executor node (take 2)

  2. Add Result Cache executor node

  3. Allow estimate_num_groups() to pass back further details about the estimation

  4. Allow users of simplehash.h to perform direct deletions

  5. Cache if PathTarget and RestrictInfos contain volatile functions

  6. Fix pull_varnos' miscomputation of relids set for a PlaceHolderVar.