Re: New GUC autovacuum_max_threshold ?

HI Nathan
> I had the opportunity to bring this patch up for discussion at the
> developer meeting at FOSDEM PGDay last week [0]. We discussed a subset
> of the topics folks have already written about in this thread, and AFAICT
> there was general approval among the attendees for proceeding with the
> "hard cap" approach due to its user-friendliness. Given that, I am
> planning to commit the attached patch in the near future (although I may
> fiddle with the commit message a bit more).
Thanks for your work on this ,that is good news.Any method that solves the
issue of vacuum being triggered by large tables is a good method.When more
comprehensive vacuum statistics become available in the future, we can
improve the calculation method then.

On Tue, Feb 4, 2025 at 3:51 AM Nathan Bossart <nathandbossart(at)gmail(dot)com>
wrote:

> I had the opportunity to bring this patch up for discussion at the
> developer meeting at FOSDEM PGDay last week [0]. We discussed a subset
> of the topics folks have already written about in this thread, and AFAICT
> there was general approval among the attendees for proceeding with the
> "hard cap" approach due to its user-friendliness. Given that, I am
> planning to commit the attached patch in the near future (although I may
> fiddle with the commit message a bit more).
>
> On Tue, Jan 14, 2025 at 11:35:17PM +0300, Alena Rybakina wrote:
> > #autovacuum_vacuum_max_threshold = 100000000 # max number of row
> updates
> > # before vacuum; -1 disables max
> > # threshold
> >
> > I think instead of "# threshold" should be "#vacuum"?
>
> That would more closely match the description of
> autovacuum_vacuum_insert_threshold, which refers to "insert vacuums," but I
> felt it would be weird to refer to "max vacuums." IMHO it is clearer to
> say that -1 disables the maximum threshold here.
>
> > There is a typo:
> >
> > * if (threshold > vac_max_thresh)
> > * threshold = vac_max_thres; - here
>
> Fixed.
>
> > I think you should add more information to the description of the
> > Relations_needs_vacanalyze function: what is vac_max_thresh and how is it
> > calculated. It is not clear what the below condition means.
> >
> > /* -1 is used to disable max threshold */
> > vac_max_thresh= (relopts&& relopts->vacuum_max_threshold>= -1)
> > ? relopts->vacuum_max_threshold
> > : autovacuum_vac_max_thresh;
>
> I looked at the commentary for this function and felt that the comments for
> this new parameter are in line with the comments for all the adjacent
> parameters. There may be an opportunity to improve this commentary, but
> IMHO that would be better handled in a separate patch that improved it for
> all these parameters.
>
> [0] https://2025.fosdempgday.org/devmeeting
>
> --
> nathan
>