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From: Peter Geoghegan <pg@bowt.ie>
Date: Wed, 18 Feb 2026 00:02:34 -0500
Message-ID: <CAH2-Wz=Ag3hrX-YWQAh1NYcvV5ZUzuenVnuZ-+4w55GL6hwpAQ@mail.gmail.com>
Subject: Re: index prefetching
To: Andres Freund <andres@anarazel.de>
Cc: Tomas Vondra <tomas@vondra.me>, Alexandre Felipe <o.alexandre.felipe@gmail.com>, 
	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 Tue, Feb 17, 2026 at 8:11=E2=80=AFPM Peter Geoghegan <pg@bowt.ie> wrote:
> FWIW, the version of the patch you're using is slightly different to
> the one I have here. Since I worked on unrelated issues with things
> like the cost of rescans with nestloop joins. Another difference is
> that the memory allocation for the VM cache is now combined with the
> main batch alloc, which seems to be more cache efficient. And saves us
> memory for plain index scans.

Here's a rebased branch with all of those mostly-unrelated optimization:

https://github.com/petergeoghegan/postgres/tree/index-prefetch-master-vmcac=
he-rescan-optimizations

I suggest that you work off of this, on the off chance that these new
optimizations end up mattering. Which is quite possible with anything
that involves an index-only scan.

--=20
Peter Geoghegan