Horton

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

Andrey Borodin <x4mmm@yandex-team.ru>

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From: Andrey Borodin <x4mmm@yandex-team.ru>
To: Melanie Plageman <melanieplageman@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Andres Freund <andres@anarazel.de>, Robert Haas <robertmhaas@gmail.com>
Date: 2025-07-13T18:34:26Z
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 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'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.