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help / color / mirror / Atom feedFrom: Dmitry Dolgov <[email protected]>
To: Tomas Vondra <[email protected]>
Cc: Teodor Sigaev <[email protected]>
Cc: Gavin Flower <[email protected]>
Cc: Andres Freund <[email protected]>
Cc: Michael Paquier <[email protected]>
Cc: PostgreSQL Developers <[email protected]>
Subject: Re: POC: GROUP BY optimization
Date: Sat, 16 May 2020 14:24:31 +0200
Message-ID: <20200516122431.b7wtpm7dspsaxfro@localhost> (raw)
In-Reply-To: <20200514235220.xewrrwjvatxzn3g6@development>
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> On Fri, May 15, 2020 at 01:52:20AM +0200, Tomas Vondra wrote:
>
> I wonder if anyone has plans to try again with this optimization in v14
> cycle? The patches no longer apply thanks to the incremental sort patch,
> but I suppose fixing that should not be extremely hard.
>
> The 2020-07 CF is still a couple weeks away, but it'd be good to know if
> there are any plans to revive this. I'm willing to spend some time on
> reviewing / testing this, etc.
Yes, if you believe that this patch has potential, I would love to pick
it up again.
> I've only quickly skimmed the old thread, but IIRC there were two main
> challenges in getting the optimization right:
>
>
> 1) deciding which orderings are interesting / worth additional work
>
> I think we need to consider these orderings, in addition to the one
> specified in GROUP BY:
>
> 1) as specified in ORDER BY (if different from 1)
What is the idea behind considering this ordering?
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Subject: Re: POC: GROUP BY optimization
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