Re: Report oldest xmin source when autovacuum cannot remove tuples

On Wed, Jun 3, 2026 at 10:24 AM Shinya Kato <shinya11(dot)kato(at)gmail(dot)com> wrote:

> On Wed, Jun 3, 2026 at 10:05 AM Scott Ray <scott(at)scottray(dot)io> wrote:
> > I've been working on a view like this. It shows the horizon
> > contribution for each backend, prepared xact, replication slot, and
> > HSF walsender, broken down by class. It also shows - for each
> > contributor - how the horizon would shift if that holder were
> > removed.
> >
> > Shinya said [1] that we could have a view in the future. We could
> > have both the logging and the view call a single function that reads
> > the procArray and other sources to gather the horizon information. I
> > think the logging and the view would complement each other.
> >
> > Should I start another thread?
>

> My mild preference would be to keep the discussion on this thread,
> since the shared function design is central to both the log and the
> view and may be easier to keep aligned in one place. That said, I'm
> not strongly attached to that, so please pick whichever feels more
> convenient.

I posted a patch for the view:

https://www.postgresql.org/message-id/AT-erSWn0vFw8TYLb84jqyfxgTV21gjwEo4YJDcses8qWtDkQK_pS6g2OIfVh4-L1PPn94w8-tE1mHZactVAgxPJ8vL96MXsyAnUg2Xz-Ks=@scottray.io

I thought that posting the full patch here might confuse cfbot, so I
decided to create a new thread and CF entry.

--
Scott Ray