Re: Big performance slowdown from 11.2 to 13.3

From: David Rowley <dgrowleyml(at)gmail(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: "ldh(at)laurent-hasson(dot)com" <ldh(at)laurent-hasson(dot)com>, Peter Geoghegan <pg(at)bowt(dot)ie>, Justin Pryzby <pryzby(at)telsasoft(dot)com>, "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Big performance slowdown from 11.2 to 13.3
Date: 2021-07-22 16:04:00
Message-ID: CAApHDvo+Gb80BVPKYCwHbLa7a7ZXp9ziq9URrpQaKdvXsd46bg@mail.gmail.com
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On Fri, 23 Jul 2021 at 03:56, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> So basically, we now have a hard restriction that hashaggs can't use
> more than INT_MAX kilobytes, or approximately 2.5GB, and this use case
> is getting eaten alive by that restriction. Seems like we need to
> do something about that.

Hmm, math check?

postgres=# select pg_size_pretty(power(2,31)::numeric*1024);
pg_size_pretty
----------------
2048 GB
(1 row)

David

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