Horton

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

Melanie Plageman <melanieplageman@gmail.com>

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From: Melanie Plageman <melanieplageman@gmail.com>
To: Andrey Borodin <x4mmm@yandex-team.ru>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Andres Freund <andres@anarazel.de>, Robert Haas <robertmhaas@gmail.com>
Date: 2025-07-13T19:15:22Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Remove table_scan_analyze_next_tuple unneeded parameter OldestXmin

  2. Simplify visibility check in heap_page_would_be_all_visible()

  3. Eliminate use of cached VM value in lazy_scan_prune()

  4. Combine visibilitymap_set() cases in lazy_scan_prune()

  5. Fix const qualification in prune_freeze_setup()

  6. Simplify vacuum visibility assertion

  7. Split heap_page_prune_and_freeze() into helpers

  8. Assert that cutoffs are provided if freezing will be attempted

  9. Split PruneFreezeParams initializers to one field per line

  10. Refactor heap_page_prune_and_freeze() parameters into a struct

  11. Make heap_page_is_all_visible independent of LVRelState

  12. Inline TransactionIdFollows/Precedes[OrEquals]()

  13. Add helper for freeze determination to heap_page_prune_and_freeze

  14. Bump XLOG_PAGE_MAGIC after xl_heap_prune change

  15. Correct prune WAL record opcode name in comment

  16. Add error codes when vacuum discovers VM corruption

  17. Remove unused xl_heap_prune member, reason

  18. Remove unneeded VM pin from VM replay

  19. Add assert and log message to visibilitymap_set

  20. Add error codes to some corruption log messages

On Sun, Jul 13, 2025 at 2:34 PM Andrey Borodin <x4mmm@yandex-team.ru> wrote:
>
> > On 12 Jul 2025, at 03:19, Melanie Plageman <melanieplageman@gmail.com> wrote:
> >
> > 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 actually did remove those if you check the last version posted. I
did notice there is one remaining comment referring to
XLOG_HEAP2_VISIBLE I missed somehow, but the actual enums/macros were
removed already.

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

I added this because I noticed that it was used without validating it
was provided in that location. The last patch in the set which sets
the VM on access changes where cutoffs are used, so I noticed what I
felt was a missing assert in master while developing that page.

> 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.

Could you clarify what you mean by this? Are you talking about the
string representation of the visibility map bits in the WAL record
representations in heapdesc.c?

- Melanie