Re: Why autvacuum is not started?

On Mon, Jan 9, 2017 at 8:45 AM, Edmundo Robles <edmundo(at)sw-argos(dot)com> wrote:

> I have running Postgresql 9.4 and... if i have a table with following
> configuration:
> autovacuum_vacuum_scale_factor=0.0,
> autovacuum_analyze_scale_factor=0.0,
> autovacuum_vacuum_threshold=1000,
> autovacuum_analyze_threshold=1000,
> autovacuum_enabled=true
>
> Why autovacuum is not started if the table has more than 1000 inserts???
>

Inserts do not generate obsolete tuples, and so are not counted against
the "vacuum threshold" as described here:
https://www.postgresql.org/docs/9.4/static/routine-vacuuming.html.

But inserts can change the data distributions, so do count against "analyze
threshold".

Due to index-only-scans and freeze maps, there are reasons to revisit this
topic, so that insert only tables do get vacuumed and not just analyzed.
But that re-think has yet to be finished, and certainly won't be
back-ported to 9.4.

Cheers,

Jeff