On Tue, Sep 26, 2023 at 8:19 AM Andres Freund <andres@anarazel.de> wrote:
> However, I'm not at all convinced doing this on a system wide level is a good
> idea. Databases do often contain multiple types of workloads at the same
> time. E.g., we want to freeze aggressively in a database that has the bulk of
> its size in archival partitions but has lots of unfrozen data in an active
> partition. And databases have often loads of data that's going to change
> frequently / isn't long lived, and we don't want to super aggressively freeze
> that, just because it's a large portion of the data.
I didn't say that we should always have most of the data in the
database frozen, though. Just that we can reasonably be more lazy
about freezing the remainder of pages if we observe that most pages
are already frozen. How they got that way is another discussion.
I also think that the absolute amount of debt (measured in physical
units such as unfrozen pages) should be kept under control. But that
isn't something that can ever be expected to work on the basis of a
simple threshold -- if only because autovacuum scheduling just doesn't
work that way, and can't really be adapted to work that way.
--
Peter Geoghegan