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: Andres Freund <andres@anarazel.de>
Cc: Robert Haas <robertmhaas@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-02-19T01:00:47Z
Lists: pgsql-hackers 
On Fri, Feb 18, 2022 at 2:11 PM Andres Freund <andres@anarazel.de> wrote:
> I think it'd be good to add a few isolationtest cases for the
> can't-get-cleanup-lock paths. I think it shouldn't be hard using cursors. The
> slightly harder part is verifying that VACUUM did something reasonable, but
> that still should be doable?

We could even just extend existing, related tests, from vacuum-reltuples.spec.

Another testing strategy occurs to me: we could stress-test the
implementation by simulating an environment where the no-cleanup-lock
path is hit an unusually large number of times, possibly a fixed
percentage of the time (like 1%, 5%), say by making vacuumlazy.c's
ConditionalLockBufferForCleanup() call return false randomly. Now that
we have lazy_scan_noprune for the no-cleanup-lock path (which is as
similar to the regular lazy_scan_prune path as possible), I wouldn't
expect this ConditionalLockBufferForCleanup() testing gizmo to be too
disruptive.

-- 
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