| From: | Melanie Plageman <melanieplageman(at)gmail(dot)com> |
|---|---|
| To: | Alexander Lakhin <exclusion(at)gmail(dot)com> |
| Cc: | Andres Freund <andres(at)anarazel(dot)de>, Tomas Vondra <tomas(at)vondra(dot)me>, David Rowley <dgrowleyml(at)gmail(dot)com>, 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: | 2026-09-10 19:25:38 |
| Message-ID: | CAAKRu_bS3nfMJCF2fjE+ceb5-t=2p_VPMk2PWuVomrOFxg5DGQ@mail.gmail.com |
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On Thu, Sep 10, 2026 at 2:31 PM Melanie Plageman
<melanieplageman(at)gmail(dot)com> wrote:
>
> An adversarial LLM review of this patch series found that I call
> visibilitymap_pin() after taking a cleanup lock on the heap page in
> the on-access pruning path -- which is not good. Here is a small patch
> to fix that. Doing it before we're sure we can get the cleanup lock
> could occasionally lead to an unneeded pin, but such situations should
> be uncommon.
It also reported that since d96f87332b3 the FSM will be less up to
date on the standby since COPY FREEZE criteria for updating the FSM is
if (action == BLK_NEEDS_REDO && freespace < BLCKSZ / 5) and the old
VM record replay code had no such freespace check. I'll post a patch
to fix that tomorrow. The fix is pretty simple: just update the FSM if
the heap multi insert record sets the VM.
- Melanie
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