Horton

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

Andy Fan <zhihui.fan1213@gmail.com>

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From: Andy Fan <zhihui.fan1213@gmail.com>
To: David Rowley <dgrowleyml@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Alvaro Herrera <alvherre@alvh.no-ip.org>, Andres Freund <andres@anarazel.de>, PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>
Date: 2020-12-05T14:52:45Z
Lists: pgsql-hackers 
Thanks for working on the new version.

On Fri, Dec 4, 2020 at 10:41 PM David Rowley <dgrowleyml@gmail.com> wrote:

>
> I also
> noticed that the code I'd written to build the cache lookup expression
> included a step to deform the outer tuple. This was unnecessary and
> slowed down the expression evaluation.
>
>
I thought it would be something like my 3rd suggestion on [1], however after
I read the code,  it looked like no.  Could you explain what changes it is?
I probably missed something.

[1]
https://www.postgresql.org/message-id/CAApHDvqvGZUPKHO%2B4Xp7Lm_q1OXBo2Yp1%3D5pVnEUcr4dgOXxEg%40mail.gmail.com

-- 
Best Regards
Andy Fan

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.