From: Tom Lane <tgl@sss.pgh.pa.us>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Andres Freund <andres@anarazel.de>
Cc: Mladen Gogala <gogala.mladen@gmail.com>
Cc: pgsql-performance@lists.postgresql.org
Subject: Re: Catching up with performance & PostgreSQL 15
Date: Tue, 29 Nov 2022 09:31:36 -0500
Message-ID: <871130.1669732296@sss.pgh.pa.us> (raw)
In-Reply-To: <20221129083615.fseqfvd5svtjbrb6@alvherre.pgsql>
References: <20221129083615.fseqfvd5svtjbrb6@alvherre.pgsql>
Alvaro Herrera <alvherre@alvh.no-ip.org> writes:
> IMO it was a mistake to turn JIT on in the default config, so that's one
> thing you'll likely want to change.
I wouldn't necessarily go quite that far, but I do think that the
default cost thresholds for invoking it are enormously too low,
or else there are serious bugs in the cost-estimation algorithms
for deciding when to use it. A nearby example[1] of a sub-1-sec
partitioned query that took 30sec after JIT was enabled makes me
wonder if we're accounting correctly for per-partition JIT costs.
regards, tom lane
[1] https://www.postgresql.org/message-id/B6025887-D73F-4B5B-9925-4DA4B675F7E5%40elevated-dev.com
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, alvherre@alvh.no-ip.org, andres@anarazel.de, gogala.mladen@gmail.com, pgsql-performance@lists.postgresql.org
Subject: Re: Catching up with performance & PostgreSQL 15
In-Reply-To: <871130.1669732296@sss.pgh.pa.us>
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