Horton

Re: Removing more vacuumlazy.c special cases, relfrozenxid optimizations

Peter Geoghegan <pg@bowt.ie>

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From: Peter Geoghegan <pg@bowt.ie>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Thomas Munro <thomas.munro@gmail.com>, Andres Freund <andres@anarazel.de>, Masahiko Sawada <sawada.mshk@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-03-30T03:08:32Z
Lists: pgsql-hackers

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On Tue, Mar 29, 2022 at 11:58 AM Peter Geoghegan <pg@bowt.ie> wrote:
> > I think I understand what the first paragraph of the header comment
> > for heap_tuple_needs_freeze() is trying to say, but the second one is
> > quite confusing. I think this is again because it veers into talking
> > about what the caller should do rather than explaining what the
> > function itself does.
>
> I wouldn't have done it that way if the function wasn't called
> heap_tuple_needs_freeze().
>
> I would be okay with removing this paragraph if the function was
> renamed to reflect the fact it now tells the caller something about
> the tuple having an old XID/MXID relative to the caller's own XID/MXID
> cutoffs. Maybe the function name should be heap_tuple_would_freeze(),
> making it clear that the function merely tells caller what
> heap_prepare_freeze_tuple() *would* do, without presuming to tell the
> vacuumlazy.c caller what it *should* do about any of the information
> it is provided.

Attached is v13, which does it that way. This does seem like a real
increase in clarity, albeit one that comes at the cost of renaming
heap_tuple_needs_freeze().

v13 also addresses all of the other items from Robert's most recent
round of feedback.

I would like to commit something close to v13 on Friday or Saturday.

Thanks
-- 
Peter Geoghegan

Commits

  1. Have VACUUM warn on relfrozenxid "in the future".

  2. vacuumlazy.c: Further consolidate resource allocation.

  3. Generalize how VACUUM skips all-frozen pages.

  4. Set relfrozenxid to oldest extant XID seen by VACUUM.

  5. Doc: Add relfrozenxid Tip to XID wraparound section.

  6. vacuumlazy.c: document vistest and OldestXmin.

  7. Increase hash_mem_multiplier default to 2.0.

  8. Consolidate VACUUM xid cutoff logic.

  9. Add VACUUM instrumentation for scanned pages, relfrozenxid.

  10. Simplify lazy_scan_heap's handling of scanned pages.

  11. Try to stabilize reloptions test, again.

  12. Unify VACUUM VERBOSE and autovacuum logging.

  13. Fix possible HOT corruption when RECENTLY_DEAD changes to DEAD while pruning.

  14. pg_resetxlog: add option to set oldest xid & use by pg_upgrade

  15. Teach VACUUM to bypass unnecessary index vacuuming.

  16. Centralize horizon determination for temp tables, fixing bug due to skew.

  17. pg_surgery: Try to stabilize regression tests.

  18. Add "split after new tuple" nbtree optimization.

  19. Fix bugs in vacuum of shared rels, by keeping their relcache entries current.

  20. Avoid useless truncation attempts during VACUUM.

  21. Only skip pages marked as clean in the visibility map, if the last 32

  22. Fix recently-understood problems with handling of XID freezing, particularly