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Subject: Re: eliminate xl_heap_visible to reduce WAL (and eventually set VM
 on-access)
From: Andrey Borodin <x4mmm@yandex-team.ru>
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Date: Sun, 13 Jul 2025 23:34:26 +0500
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>,
 Andres Freund <andres@anarazel.de>,
 Robert Haas <robertmhaas@gmail.com>
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To: Melanie Plageman <melanieplageman@gmail.com>
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> On 12 Jul 2025, at 03:19, Melanie Plageman <melanieplageman@gmail.com> =
wrote:
>=20
> remove the xl_heap_visible struct

Same goes for VISIBILITYMAP_XLOG_CATALOG_REL and XLOG_HEAP2_VISIBLE. But =
please do not rush to remove it, perhaps I will have a more exhaustive =
list later. Currently the patch set is expected to be unpolished.
I just need to absorb all effects to have a high-level evaluation of the =
patch set effect.

I'm still trying to grasp connection of first patch with =
Assert(prstate->cutoffs) to other patches;

Also, I'd prefer "page is not marked all-visible but visibility map bit =
is set in relation" to emit XX001 for monitoring reasons, but again, =
this is small note, while I need a broader picture.

So far I do not see any general problems in delegating redo work from =
xl_heap_visible to other record. FWIW I observed several cases of VM =
corruptions that might be connected to the fact that we log VM changes =
independently of data changes that caused VM to change. But I have no =
real evidence or understanding what happened.


Best regards, Andrey Borodin.=