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: Robert Haas <robertmhaas@gmail.com>
Cc: Masahiko Sawada <sawada.mshk@gmail.com>, Andres Freund <andres@anarazel.de>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-02-12T04:30:30Z
Lists: pgsql-hackers

Attachments

On Sat, Jan 29, 2022 at 8:42 PM Peter Geoghegan <pg@bowt.ie> wrote:
> Attached is v7, a revision that overhauls the algorithm that decides
> what to freeze. I'm now calling it block-driven freezing in the commit
> message. Also included is a new patch, that makes VACUUM record zero
> free space in the FSM for an all-visible page, unless the total amount
> of free space happens to be greater than one half of BLCKSZ.

I pushed the earlier refactoring and instrumentation patches today.

Attached is v8. No real changes -- just a rebased version.

It will be easier to benchmark and test the page-driven freezing stuff
now, since the master/baseline case will now output instrumentation
showing how relfrozenxid has been advanced (if at all) -- whether (and
to what extent) each VACUUM operation advances relfrozenxid can now be
directly compared, just by monitoring the log_autovacuum_min_duration
output for a given table over time.

--
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