Horton

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

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Greg Stark <stark@mit.edu>
Cc: Peter Geoghegan <pg@bowt.ie>, Andres Freund <andres@anarazel.de>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Masahiko Sawada <sawada.mshk@gmail.com>
Date: 2022-02-07T14:53:13Z
Lists: pgsql-hackers 
On Fri, Feb 4, 2022 at 10:21 PM Greg Stark <stark@mit.edu> wrote:
> By far the majority of anti-wraparound vacuums are triggered by tables
> that are very large and so don't trigger regular vacuums for "long
> periods" of time and consistently hit the anti-wraparound threshold
> first.

That's interesting, because my experience is different. Most of the
time when I get asked to look at a system, it turns out that there is
a prepared transaction or a forgotten replication slot and nobody
noticed until the system hit the wraparound threshold. Or occasionally
a long-running transaction or a failing/stuck vacuum that has the same
effect.

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

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