Horton

Re: New strategies for freezing, advancing relfrozenxid early

Peter Geoghegan <pg@bowt.ie>

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From: Peter Geoghegan <pg@bowt.ie>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Andres Freund <andres@anarazel.de>, Jeff Davis <pgsql@j-davis.com>, Matthias van de Meent <boekewurm+postgres@gmail.com>, John Naylor <john.naylor@enterprisedb.com>, Justin Pryzby <pryzby@telsasoft.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2023-01-26T06:38:49Z
Lists: pgsql-hackers 
On Wed, Jan 25, 2023 at 8:24 PM Peter Geoghegan <pg@bowt.ie> wrote:
> > I think we're on a very dangerous path here. I want VACUUM to be
> > better as the next person, but I really don't believe that's the
> > direction we're headed. I think if we release like this, we're going
> > to experience more VACUUM pain, not less. And worse still, I don't
> > think anyone other than Peter and Andres is going to understand why
> > it's happening.
>
> I think that the only sensible course of action at this point is for
> me to revert the page-level freezing commit from today, and abandon
> all outstanding work on VACUUM. I will still stand by the basic
> page-level freezing work, at least to the extent that I am able to.

I have now reverted today's commit. I have also withdrawn all
remaining work from the patch series as a whole, which is reflected in
the CF app. Separately, I have withdrawn 2 other VACUUM related
patches of mine via the CF app: the antiwraparound autovacuum patch
series, plus a patch that did some further work on freezing
MultiXacts.

I have no intention of picking any of these patches back up again. I
also intend to completely avoid new work on both VACUUM and
autovacuum, not including ambulkdelete() code run by index access
methods. I will continue to do maintenance and bugfix work when it
happens to involve VACUUM, though.

For the record, in case it matters: I certainly have no objection to
anybody else picking up any of this unfinished work for themselves, in
part or in full.

--
Peter Geoghegan

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