| From: | David Rowley <dgrowleyml(at)gmail(dot)com> |
|---|---|
| To: | Thomas Munro <thomas(dot)munro(at)gmail(dot)com> |
| Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, PostgreSQL Developers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Andres Freund <andres(at)anarazel(dot)de> |
| Subject: | Re: Hybrid Hash/Nested Loop joins and caching results from subplans |
| Date: | 2020-08-31 21:59:05 |
| Message-ID: | CAApHDvpDb5XDSDQJWT8DbY8TL+PVbozRaEyXxi8wzJOuN-jEgA@mail.gmail.com |
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| Lists: | pgsql-hackers |
Thanks for chipping in here.
On Mon, 31 Aug 2020 at 17:57, Thomas Munro <thomas(dot)munro(at)gmail(dot)com> wrote:
> I wonder what it would take to overcome the overheads of the separate
> Result Cache node, with techniques to step out of the way or something
> like that.
So far it looks like there are more overheads to having the caching
done inside nodeNestloop.c. See [1]. Perhaps there's something that
can be done to optimise away the needless MinimalTuple deform that I
mentioned there, but for now, performance-wise, we're better off
having a separate node.
David
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