Re: Intermittent buildfarm failures on wrasse

Hi,

On 2022-04-15 09:29:20 -0700, Peter Geoghegan wrote:
> On Fri, Apr 15, 2022 at 8:14 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> > BTW, before I forget: the wording of this log message is just awful.
> > On first sight, I thought that it meant that we'd computed OldestXmin
> > a second time and discovered that it advanced by 26 xids while the VACUUM
> > was running.
>
> > "removable cutoff: %u, which was %d xids old when operation ended\n"
>
> How the output appears when placed right before the output describing
> how VACUUM advanced relfrozenxid is an important consideration. I want
> the format and wording that we use to imply a relationship between
> these two things. Right now, that other line looks like this:
>
> "new relfrozenxid: %u, which is %d xids ahead of previous value\n"
>
> Do you think that this juxtaposition works well?

I don't think they're actually that comparable. One shows how much
relfrozenxid advanced, to a large degree influenced by the time between
aggressive (or "unintentionally aggressive") vacuums. The other shows
the age of OldestXmin at the end of the vacuum. Which is influenced by
what's currently running.

Greetings,

Andres Freund