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help / color / mirror / Atom feedFrom: Robert Haas <[email protected]>
To: Richard Guo <[email protected]>
Cc: Paul George <[email protected]>
Cc: Andy Fan <[email protected]>
Cc: PostgreSQL-development <[email protected]>
Cc: [email protected]
Subject: Re: Eager aggregation, take 3
Date: Thu, 29 Aug 2024 08:40:09 -0400
Message-ID: <CA+TgmoYdO68GtU9WZ1_a+gJs7fZ96sNraxyvVwu4iRYv4kYmLQ@mail.gmail.com> (raw)
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On Wed, Aug 28, 2024 at 10:26 PM Richard Guo <[email protected]> wrote:
> Yeah, I'm concerned about this too. In addition to the inaccuracies
> in aggregation estimates, our estimates for joins are sometimes not
> very accurate either. All this are likely to result in regressions
> with eager aggregation in some cases. Currently I don't have a good
> answer to this problem. Maybe we can run some benchmarks first and
> investigate the regressions discovered on a case-by-case basis to better
> understand the specific issues.
While it's true that we can make mistakes during join estimation, I
believe aggregate estimation tends to be far worse.
--
Robert Haas
EDB: http://www.enterprisedb.com
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Subject: Re: Eager aggregation, take 3
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