Re: Why isn't my table auto-analyzed/vacuumed?

On Fri, Oct 31, 2025 at 4:52 PM Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com>
wrote:

> On 10/31/25 13:03, Dimitrios Apostolou wrote:
> > On Thursday 2025-10-30 18:00, Ron Johnson wrote:
> >
> >>
> >> > SELECT reltuples FROM pg_class WHERE relname =
> >> 'test_runs_summarized_per_function' \gx
> >> -[ RECORD 1 ]-----------
> >> reltuples | 6.061923e+09
> >>
> >> > SELECT name,setting FROM pg_settings WHERE name ILIKE '%factor%'
> ;
> >> name | setting
> >> ---------------------------------------+---------
> >> autovacuum_analyze_scale_factor | 0.1
> >>
> >>
> >> 0.1 means 10%.
> >>
> >> autovacuum_vacuum_insert_scale_factor | 0.2
> >> autovacuum_vacuum_scale_factor | 0.2
> >> recursive_worktable_factor | 10
> >>
> >>
> >> n_mod_since_analyze=423101205
> >> n_live_tup=6484485348
> >>
> >> n_mod_since_analyze/n_live_tup = 6.5%
> >>
> >> How can I get more info from postgres on the autovacuum logic?
> >>
> >>
> >> I would:
> >> 1) manually VACUUM ANALYZE the table,
> >> 2) drop the three autovacuum_*_scale_factor values down to 0.03 (i.e.
> >> 3%),
> >
> > Reporting back, after reducing the values, the table has been picked up
> > for both autovacuum and analyze. Thank you for the immediate feedback!
> >
> > Since I had spent some time looking into these values and was "certain"
> > that they were % while they are apparently *not*, I'm wondering if
> > max_val=100 is there because of historical reasons, and if it would make
> > sense to change it to 1.
>
> But they are:
>
> 0.1/1 is 10% as is 10/100.
>

And 0.1/100 = 0.1%.

Dimitrios is right: it's misleading to have a default of 0.1 that means
10%, but also have the max value be 100 because 10 is 10% of 100.

https://www.postgresql.org/docs/17/runtime-config-autovacuum.html#GUC-AUTOVACUUM-ANALYZE-SCALE-FACTOR
certainly doesn't mention that you can use either reals (0,1] or integers
(0,100].

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