Horton

Re: BUG #17257: (auto)vacuum hangs within lazy_scan_prune()

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Alexander Lakhin <exclusion@gmail.com>
Cc: PostgreSQL mailing lists <pgsql-bugs@lists.postgresql.org>
Date: 2024-04-15T16:17:22Z
Lists: pgsql-bugs

Commits

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  1. Ensure vacuum removes all visibly dead tuples older than OldestXmin

  2. Combine freezing and pruning steps in VACUUM

  3. Handle non-chain tuples outside of heap_prune_chain()

  4. Fix false reports in pg_visibility

  5. Remove retry loop in heap_page_prune().

  6. vacuumlazy.c: document vistest and OldestXmin.

  7. Deduplicate choice of horizon for a relation procarray.c.

  8. Remove tupgone special case from vacuumlazy.c.

  9. Simplify state managed by VACUUM.

  10. Recycle nbtree pages deleted during same VACUUM.

  11. snapshot scalability: Don't compute global horizons while building snapshots.

  12. Raise error when affecting tuple moved into different partition.

On Tue, Apr 9, 2024 at 4:00 PM Alexander Lakhin <exclusion@gmail.com> wrote:
> I was talking about both — dad1539ae eliminated the bug (judging from the
> repro) on REL_14_STABLE, and I suppose that 18b87b201 did the same for
> REL_15_STABLE/REL_16_STABLE...
> (On 18b87b201~1 I've got (twice):
> TRAP: FailedAssertion("HeapTupleHeaderIsHeapOnly(htup)", File: "pruneheap.c", Line: 964, PID: 1854895)

I'm inclined to believe that there's a residual bug here, or at least
that there was one before 6dbb490261a6170a3fc3e326c6983ad63e795047 and
related commits. But if we can't reproduce the issue, I don't know how
much we can realistically do here. This logic is so complicated and so
tricky that I don't trust myself to say "yes, this is definitely
wrong, and after change XYZ it's definitely right." The bug is as
likely to be in my analysis as it is to be in the code itself.

-- 
Robert Haas
EDB: http://www.enterprisedb.com