Re: eliminate xl_heap_visible to reduce WAL (and eventually set VM on-access)

From: Melanie Plageman <melanieplageman(at)gmail(dot)com>
To: Tomas Vondra <tomas(at)vondra(dot)me>
Cc: Andres Freund <andres(at)anarazel(dot)de>, Kirill Reshke <reshkekirill(at)gmail(dot)com>, Chao Li <li(dot)evan(dot)chao(at)gmail(dot)com>, Andrey Borodin <x4mmm(at)yandex-team(dot)ru>, Xuneng Zhou <xunengzhou(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Heikki Linnakangas <hlinnaka(at)iki(dot)fi>
Subject: Re: eliminate xl_heap_visible to reduce WAL (and eventually set VM on-access)
Date: 2026-03-25 23:14:17
Message-ID: CAAKRu_ZrDadxmGepBwPZ03yAKnMxwsHYn8SK9Gg7VqigLLVUWg@mail.gmail.com
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On Wed, Mar 25, 2026 at 2:54 PM Melanie Plageman
<melanieplageman(at)gmail(dot)com> wrote:
>
> I'm trying to think of cases where the two approaches would differ so
> I can decide which to do.
>
> > 0003
> >
> > - Half the "beginscan" calls use a ternary operator directly, half sets
> > a variable first (and then uses that). Often mixed in the same file.
> > Shouldn't it be a bit consistent?
>
> Indeed.

Attached v46 addresses your feedback and has a bit of assorted cleanup in it.

I started wondering if table_beginscan_strat() is a bit weird now
because it has two boolean arguments that are basically just
SO_ALLOW_STRAT and SO_ALLOW_SYNC -- so those are kind of letting the
user set "internal" flags. Anyway, I'm not sure we should do anything
about it, but it got me thinking.

- Melanie

Attachment Content-Type Size
v46-0001-Track-which-relations-are-modified-by-a-query.patch text/x-patch 6.3 KB
v46-0002-Thread-flags-through-begin-scan-APIs.patch text/x-patch 34.0 KB
v46-0003-Pass-down-information-on-table-modification-to-s.patch text/x-patch 9.5 KB
v46-0004-Allow-on-access-pruning-to-set-pages-all-visible.patch text/x-patch 9.2 KB
v46-0005-Set-pd_prune_xid-on-insert.patch text/x-patch 8.8 KB

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