On Wed, Sep 27, 2023 at 12:45 PM Robert Haas <robertmhaas@gmail.com> wrote:
> > One big sticking point for me (brought up elsewhere in this thread, but,
> > AFAICT never resolved) is that it seems like the fact that we mark pages
> > all-visible even when not freezing them means that no matter what
> > heuristic we use, we won't have the opportunity to freeze the pages we
> > most want to freeze.
>
> The only solution to this problem that I can see is what Peter
> proposed earlier: if we're not prepared to freeze the page, then don't
> mark it all-visible either. This might be the right thing to do, and
> if it is, we could even go further and get rid of the two as separate
> concepts completely. However, I think it would be OK to leave all of
> that to one side for the moment, *especially* if we adopt some
> proposal that does a lot more opportunistic freezing than we do
> currently. Because then the problem just wouldn't come up nearly as
> much as it does now. One patch can't fix everything, and shouldn't
> try.
I guess that it might make sense to leave the issue of
all-visible-only pages out of it for the time being. I would just
point out that that means that you'll be limited to adding strictly
opportunistic behaviors, where it just so happens that VACUUM stumbles
upon pages where freezing early likely makes sense. Basically, an
incremental improvement on the FPI thing -- not the sort of thing
where I'd expect Melanie's current approach of optimizing a whole
cross-section of representative workloads to really help with.
I have a separate concern about it that I'll raise shortly, in my
response to Andres.
--
Peter Geoghegan