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: Peter Geoghegan <pg@bowt.ie>
Cc: Masahiko Sawada <sawada.mshk@gmail.com>, Andres Freund <andres@anarazel.de>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-01-20T19:33:03Z
Lists: pgsql-hackers 
On Thu, Jan 20, 2022 at 11:45 AM Peter Geoghegan <pg@bowt.ie> wrote:
> My thinking on vacuum_freeze_min_age has shifted very slightly. I now
> think that I'll probably need to keep it around, just so things like
> VACUUM FREEZE (which sets vacuum_freeze_min_age to 0 internally)
> continue to work. So maybe its default should be changed to -1, which
> is interpreted as "whatever autovacuum_freeze_max_age/2 is". But it
> should still be greatly deemphasized in user docs.

I like that better, because it lets us retain an escape valve in case
we should need it. I suggest that the documentation should say things
like "The default is believed to be suitable for most use cases" or
"We are not aware of a reason to change the default" rather than
something like "There is almost certainly no good reason to change
this" or "What kind of idiot are you, anyway?" :-)

-- 
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