Horton

Re: New strategies for freezing, advancing relfrozenxid early

John Naylor <john.naylor@enterprisedb.com>

View thread View on postgr.es
From: John Naylor <john.naylor@enterprisedb.com>
To: Andres Freund <andres@anarazel.de>
Cc: Peter Geoghegan <pg@bowt.ie>, Jeff Davis <pgsql@j-davis.com>, Matthias van de Meent <boekewurm+postgres@gmail.com>, Justin Pryzby <pryzby@telsasoft.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Robert Haas <robertmhaas@gmail.com>
Date: 2023-01-26T04:12:22Z
Lists: pgsql-hackers 
On Thu, Jan 26, 2023 at 10:11 AM Andres Freund <andres@anarazel.de> wrote:

> I am. Just not every tradeoff. I just don't see any useful tradeoffs
purely
> based on the relation size.

I expressed reservations about relation size six weeks ago:

On Wed, Dec 14, 2022 at 12:16 AM Peter Geoghegan <pg@bowt.ie> wrote:
>
> On Tue, Dec 13, 2022 at 12:29 AM John Naylor
> <john.naylor@enterprisedb.com> wrote:
> > If the number of unfrozen heap pages is the thing we care about,
perhaps that, and not the total size of the table, should be the parameter
that drives freezing strategy?
>
> That's not the only thing we care about, though.

That was followed by several paragraphs that never got around to explaining
why table size should drive freezing strategy. Review is a feedback
mechanism alerting the patch author to possible problems. Listening to
feedback is like vacuum, in a way: If it hurts, you're not doing it enough.

--
John Naylor
EDB: http://www.enterprisedb.com

Commits

  1. Revert "Add eager and lazy freezing strategies to VACUUM."

  2. Add eager and lazy freezing strategies to VACUUM.

  3. Refine the definition of page-level freezing.

  4. Avoid special XID snapshotConflictHorizon values.

  5. Add page-level freezing to VACUUM.

  6. Remove overzealous MultiXact freeze assertion.

  7. Refactor how VACUUM passes around its XID cutoffs.

  8. Deduplicate freeze plans in freeze WAL records.

  9. Set relfrozenxid to oldest extant XID seen by VACUUM.

  10. Only skip pages marked as clean in the visibility map, if the last 32

  11. Add vacuum_freeze_table_age GUC option, to control when VACUUM should