Horton

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

Thomas Munro <thomas.munro@gmail.com>

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From: Thomas Munro <thomas.munro@gmail.com>
To: Peter Geoghegan <pg@bowt.ie>
Cc: Robert Haas <robertmhaas@gmail.com>, Andres Freund <andres@anarazel.de>, Masahiko Sawada <sawada.mshk@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-03-23T21:02:48Z
Lists: pgsql-hackers 
On Thu, Mar 24, 2022 at 9:59 AM Peter Geoghegan <pg@bowt.ie> wrote:
> On Wed, Mar 23, 2022 at 1:53 PM Robert Haas <robertmhaas@gmail.com> wrote:
> > And therefore I favor defining it to mean that we don't
> > skip any work at all.
>
> But even today DISABLE_PAGE_SKIPPING won't do pruning when we cannot
> acquire a cleanup lock on a page, unless it happens to have XIDs from
> before FreezeLimit (which is probably 50 million XIDs behind
> OldestXmin, the vacuum_freeze_min_age default). I don't see much
> difference.

Yeah, I found it confusing that DISABLE_PAGE_SKIPPING doesn't disable
all page skipping, so 3414099c turned out to be not enough.

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