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From: Stephen Frost <sfrost@snowman.net>
To: Charles <peacech@gmail.com>
Cc: David Rowley <dgrowleyml@gmail.com>
Cc: Jeff Janes <jeff.janes@gmail.com>
Cc: pgsql-bugs@lists.postgresql.org
Subject: Re: Query run in 27s with 15.2 vs 37ms with 14.6
Date: Tue, 21 Feb 2023 11:35:54 -0500
Message-ID: <Y/Ty6roAf76C6Pzw@tamriel.snowman.net> (raw)
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	<CABthHP-XJXF8L_GLnWvU6Mm09B3_gJV8fy1uAPOFhLrAOPopLg@mail.gmail.com>

Greetings,

* Charles (peacech@gmail.com) wrote:
> Thank you for the hint. I think this is it. random_page_cost was set to 1.1
> in 14.6 (the data directory is located in a ssd). When upgrading to 15.2 I
> thought that ssd random seek time is not that close to sequential seek
> time, so I revert it back to 4.

In the future, you might want to be sure and include 'settings' in your
EXPLAIN options, eg:

EXPLAIN (ANALYZE, BUFFERS, SETTINGS) query ...

so that you see what non-default planner settings are set when the query
is being planned.

Thanks,

Stephen

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