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: Robert Haas <robertmhaas@gmail.com>
Cc: Andres Freund <andres@anarazel.de>, Kirill Reshke <reshkekirill@gmail.com>, Andrey Borodin <x4mmm@yandex-team.ru>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Heikki Linnakangas <hlinnaka@iki.fi>
Date: 2025-09-08T18:32:29Z
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 Mon, Sep 8, 2025 at 12:41 PM Robert Haas <robertmhaas@gmail.com> wrote:
>
> On Fri, Sep 5, 2025 at 6:20 PM Melanie Plageman
> <melanieplageman@gmail.com> wrote:
> > yikes, you are right about the "reason" member. Attached 0002 removes
> > it, and I'll go ahead and fix it in the back branches too.
>
> I think changing this in the back-branches is a super-bad idea. If you
> want, you can add a comment in the back-branches saying "oops, we
> shipped a field that isn't used for anything", but changing the struct
> definition is very likely to make 0 people happy and >0 people
> unhappy. On the other hand, changing this in master is a good idea and
> you should go ahead and do that before this creates any more
> confusion.

Yes, that makes 100% sense. It should have occurred to me. I've pushed
the commit to master. I didn't put an updated set of patches here in
case someone was already reviewing them, as nothing else has changed.

- Melanie