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From: Robert Haas <[email protected]>
To: lakshmi <[email protected]>
Cc: Kirill Reshke <[email protected]>
Cc: pgsql-hackers <[email protected]>
Subject: Re: Use log_newpage_range in HASH index build
Date: Sun, 26 Apr 2026 13:12:06 -0400
Message-ID: <CA+TgmoZRs3ArQC_rkVCx_Q7rWCM+QF-Q6ERRYUaN4tUvr+rd7w@mail.gmail.com> (raw)
In-Reply-To: <CAEvyyTjGtYRq3Aa0tY6=_QGV6z+6KTQVF=J75Acx2L6i0JOkGw@mail.gmail.com>
References: <CALdSSPgu6fnoOYzgiFF4_Etr96zEHvSwvYJDemc3o++EZbUQMA@mail.gmail.com>
	<CAEvyyTjUTLXvrme3CNMjJYwA9j4usrq53PyBPv47Apk58Qz+GA@mail.gmail.com>
	<CAEvyyTjGtYRq3Aa0tY6=_QGV6z+6KTQVF=J75Acx2L6i0JOkGw@mail.gmail.com>

On Mon, Jan 5, 2026 at 3:48 AM lakshmi <[email protected]> wrote:
> Following up on my earlier note, I implemented the proposed HASH overflow page reuse enhancement.Recently freed overflow pages are recorded in
> _hash_freeovflpage( ),and _hash_addovflpage( ) now prefers reusing those pages during allocation before falling back to the bitmap scan.
>
> The change is backend-local and allocation-only,with no WAL or on-disk format changes.I verified correctness using index build/drop and VACUUM cycles,and confirmed WAL neutrality by comparing WAL generated during HASH index builds with and without this change (no  observable difference beyond normal noise).
>
> The patch is attached for review.Feedback is welcome.

It is probably best to start a separate email thread specifically
about this patch, because it's doing something quite different from
the original patch. I suggest presenting some specific performance
results, as it's not very clear how much benefit this might have. It
might be good to test a favorable scenario and also an unfavorable
scenario, describing and showing results for each.

-- 
Robert Haas
EDB: http://www.enterprisedb.com

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