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In-Reply-To: <931afce3-8c86-4c96-9861-0ffa17c6560f@vondra.me>
From: Peter Geoghegan <pg@bowt.ie>
Date: Thu, 28 Aug 2025 19:57:17 -0400
Message-ID: 
 <CAH2-Wz=DfvzasnzLv43cu36Q1Ca8Qi70_JjZ7SRbNhDwwgvirg@mail.gmail.com>
Subject: Re: index prefetching
To: Tomas Vondra <tomas@vondra.me>
Cc: Andres Freund <andres@anarazel.de>, Thomas Munro <thomas.munro@gmail.com>,
	Nazir Bilal Yavuz <byavuz81@gmail.com>, Robert Haas <robertmhaas@gmail.com>,
	Melanie Plageman <melanieplageman@gmail.com>,
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>,
 Georgios <gkokolatos@protonmail.com>,
	Konstantin Knizhnik <knizhnik@garret.ru>, Dilip Kumar <dilipbalaut@gmail.com>
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On Thu, Aug 28, 2025 at 7:52=E2=80=AFPM Tomas Vondra <tomas@vondra.me> wrot=
e:
> Use this branch:
>
>   https://github.com/tvondra/postgres/commits/index-prefetch-master/
>
> and then Thomas' patch that increases the prefetch distance:
>
>
> https://www.postgresql.org/message-id/CA%2BhUKGL2PhFyDoqrHefqasOnaXhSg48t=
1phs3VM8BAdrZqKZkw%40mail.gmail.com
>
> (IIRC there's a trivial conflict in read_stream_reset.).

I found it quite hard to apply Thomas' patch. There's actually 3
patches, with 2 earlier patches needed for earlier in the thread. And,
there were significant merge conflicts to work around.

I'm not sure that Thomas'/your patch to ameliorate the problem on the
read stream side is essential here. Perhaps Andres can just take a
look at the test case + feature branch, without the extra patches.
That way he'll be able to see whatever the immediate problem is, which
might be all we need.

--=20
Peter Geoghegan