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: Greg Stark <stark@mit.edu>
Cc: Andres Freund <andres@anarazel.de>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Masahiko Sawada <sawada.mshk@gmail.com>
Date: 2022-02-05T04:20:50Z
Lists: pgsql-hackers 
On Fri, Feb 4, 2022 at 10:44 PM Peter Geoghegan <pg@bowt.ie> wrote:
> Right - it's practically inevitable that you'll need an
> anti-wraparound VACUUM to advance relfrozenxid right now. Technically
> it's possible to advance relfrozenxid in any VACUUM, but in practice
> it just never happens on a large table. You only need to get unlucky
> with one heap page, either by failing to get a cleanup lock, or (more
> likely) by setting even one single page all-visible but not all-frozen
> just once (once in any VACUUM that takes place between anti-wraparound
> VACUUMs).

Minor correction: That's a slight exaggeration, since we won't skip
groups of all-visible pages that don't exceed SKIP_PAGES_THRESHOLD
blocks (32 blocks).

-- 
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