Horton

Re: New strategies for freezing, advancing relfrozenxid early

Matthias van de Meent <boekewurm+postgres@gmail.com>

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From: Matthias van de Meent <boekewurm+postgres@gmail.com>
To: Peter Geoghegan <pg@bowt.ie>
Cc: Jeff Davis <pgsql@j-davis.com>, John Naylor <john.naylor@enterprisedb.com>, Andres Freund <andres@anarazel.de>, Justin Pryzby <pryzby@telsasoft.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2023-01-25T15:51:33Z
Lists: pgsql-hackers 
On Tue, 24 Jan 2023 at 23:50, Peter Geoghegan <pg@bowt.ie> wrote:
>
> On Mon, Jan 16, 2023 at 5:55 PM Peter Geoghegan <pg@bowt.ie> wrote:
> > 0001 (the freezing strategies patch) is now committable IMV. Or at
> > least will be once I polish the docs a bit more. I plan on committing
> > 0001 some time next week, barring any objections.
>
> I plan on committing 0001 (the freezing strategies commit) tomorrow
> morning, US Pacific time.
>
> Attached is v17. There are no significant differences compared to v17.
> I decided to post a new version now, ahead of commit, to show how I've
> cleaned up the docs in 0001 -- docs describing the new GUC, freeze
> strategies, and so on.

LGTM, +1 on 0001

Some more comments on 0002:

> +lazy_scan_strategy(LVRelState *vacrel, bool force_scan_all)
> scanned_pages_lazy & scanned_pages_eager

We have not yet scanned the pages, so I suggest plan/scan_pages_eager
and *_lazy as variable names instead, to minimize confusion about the
naming.

I'll await the next iteration of 0002 in which you've completed more
TODOs before I'll dig deeper into that patch.


Kind regards,

Matthias van de Meent

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