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: Andres Freund <andres@anarazel.de>
Cc: Kirill Reshke <reshkekirill@gmail.com>, Robert Haas <robertmhaas@gmail.com>, Andrey Borodin <x4mmm@yandex-team.ru>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Heikki Linnakangas <hlinnaka@iki.fi>, Chao Li <li.evan.chao@gmail.com>
Date: 2025-12-16T16:58:50Z
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

Attachments

On Wed, Dec 3, 2025 at 6:07 PM Melanie Plageman
<melanieplageman@gmail.com> wrote:
>
> If we're just talking about the renaming, looking at procarray.c, it
> is full of the word "removable" because its functions were largely
> used to examine and determine if everyone can see an xmax as committed
> and thus if that tuple is removable from their perspective. But
> nothing about the code that I can see means it has to be an xmax. We
> could just as well use the functions to determine if everyone can see
> an xmin as committed.

In the attached v27, I've removed the commit that renamed functions in
procarray.c. I've added a single wrapper GlobalVisTestXidNotRunning()
that is used in my code where I am testing live tuples. I think you'll
find that I've addressed all of your review comments now -- as I've
also gotten rid of the confusing blk_known_av logic through a series
of refactors.

The one outstanding point is which commits should bump
XLOG_PAGE_MAGIC. (also review of the reworked patches).

- Melanie