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

Kirill Reshke <reshkekirill@gmail.com>

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From: Kirill Reshke <reshkekirill@gmail.com>
To: Melanie Plageman <melanieplageman@gmail.com>
Cc: Chao Li <li.evan.chao@gmail.com>, Andres Freund <andres@anarazel.de>, Andrey Borodin <x4mmm@yandex-team.ru>, Xuneng Zhou <xunengzhou@gmail.com>, Robert Haas <robertmhaas@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Heikki Linnakangas <hlinnaka@iki.fi>
Date: 2026-03-17T09:05:16Z
Lists: pgsql-hackers 
On Mon, 16 Mar 2026 at 19:53, Melanie Plageman
<melanieplageman@gmail.com> wrote:
>
> On Sun, Mar 15, 2026 at 3:10 PM Melanie Plageman
> <melanieplageman@gmail.com> wrote:
> >
> > I've pushed a few more of the trivial commits in the set. Attached v38
> > has the remaining patches.
>
> Looks like cfbot wasn't able to rebase v38 on its own for some reason.
> v39 attached.
>
> - Melanie

Hi!

I did take a quick look on v38-v39.

0001 & 0003 looks ok.

> From 788860ded375fcf744201347b9dcbf496070bfb5 Mon Sep 17 00:00:00 2001
> From: Melanie Plageman <melanieplageman@gmail.com>
> Date: Wed, 25 Feb 2026 16:48:19 -0500
> Subject: [PATCH v39 02/12] Add pruning fast path for all-visible and
 all-frozen pages

For the record, does this work with DISABLE_PAGE_SKIPPING? I think we
don't  want the server to "fast-path" in case this option is set by
the user...



-- 
Best regards,
Kirill Reshke

Commits

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

  1. Stabilize btree_gist test against on-access VM setting

  2. Stabilize plancache test against on-access VM setting

  3. Make local buffers pin limit more conservative

  4. Update FSM during prune/freeze replay even if freespace is zero

  5. Pass down information on table modification to scan nodes

  6. Thread flags through begin-scan APIs

  7. Remove PlannedStmt->resultRelations in favor of resultRelationRelids

  8. Make it cheap to check if a relation is modified by a query

  9. Keep newest live XID up-to-date even if page not all-visible

  10. Add pruning fast path for all-visible and all-frozen pages

  11. Detect and fix visibility map corruption in more cases

  12. Save vmbuffer in heap-specific scan descriptors for on-access pruning

  13. Avoid BufferGetPage() calls in heap_update()

  14. Initialize missing fields in CreateExecutorState()

  15. Prefix PruneState->all_{visible,frozen} with set_

  16. Add PageGetPruneXid() helper

  17. Move commonly used context into PruneState and simplify helpers

  18. Remove table_scan_analyze_next_tuple unneeded parameter OldestXmin

  19. Simplify visibility check in heap_page_would_be_all_visible()

  20. Rename LVRelState VM-related logging counters

  21. Fix flakiness in the pg_visibility VM-only vacuum test by using a temporary table.

  22. Refactor lazy_scan_prune() VM clear logic into helper

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

  24. Combine visibilitymap_set() cases in lazy_scan_prune()

  25. Fix const qualification in prune_freeze_setup()

  26. Simplify vacuum visibility assertion

  27. Split heap_page_prune_and_freeze() into helpers

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

  29. Split PruneFreezeParams initializers to one field per line

  30. Refactor heap_page_prune_and_freeze() parameters into a struct

  31. Make heap_page_is_all_visible independent of LVRelState

  32. Inline TransactionIdFollows/Precedes[OrEquals]()

  33. Add helper for freeze determination to heap_page_prune_and_freeze

  34. Bump XLOG_PAGE_MAGIC after xl_heap_prune change

  35. Correct prune WAL record opcode name in comment

  36. Add error codes when vacuum discovers VM corruption

  37. Remove unused xl_heap_prune member, reason

  38. Remove unneeded VM pin from VM replay

  39. Add assert and log message to visibilitymap_set

  40. Stamp HEAD as 19devel.

  41. Add error codes to some corruption log messages