Re: Decoupling antiwraparound autovacuum from special rules around auto cancellation

On Fri, 2022-11-25 at 14:47 -0800, Peter Geoghegan wrote:
> Attached WIP patch invents the idea of a regular autovacuum that is
> tasked with advancing relfrozenxid -- which is really just another
> trigger criteria, reported on in the server log in its autovacuum
> reports. Of course we retain the idea of antiwraparound autovacuums.
> The only difference is that they are triggered when table age has
> advanced by twice the usual amount, which is presumably only possible
> because a regular autovacuum couldn't start or couldn't complete in
> time (most likely due to continually being auto-cancelled).
>
> As I said before, I think that the most important thing is to give
> regular autovacuuming a chance to succeed. The exact approach taken
> has a relatively large amount of slack, but that probably isn't
> needed. So the new antiwraparound cutoffs were chosen because they're
> easy to understand and remember, which is fairly arbitrary.

The target is a table that receives no DML at all, right?
I think that is a good idea.
Wouldn't it make sense to trigger that at *half* "autovacuum_freeze_max_age"?

Yours,
Laurenz Albe