Re: autovacuum_analyze_scale_factor and autovacuum_analyze_scale_factor

On Thu, 2021-01-07 at 10:56 -0600, Henry Francisco Garcia Cortez wrote:
> El mié, 6 ene 2021 a las 19:53, Laurenz Albe (<laurenz(dot)albe(at)cybertec(dot)at>) escribió:
>
> > On Wed, 2021-01-06 at 11:05 -0600, Henry Francisco Garcia Cortez wrote:
> > > I have a question why settings default postgresql has autovacuum_vacuum_scale_factor in 0.2
> > > is higher than autovacuum_analyze_scale_factor 0.1, so If want to tune these parameters,
> > > I always must leave autovacuum_vacuum_scale_factor higher than autovacuum_analyze_scale_factor,
> > > for instance I wanted to leave autovacuum_vacuum_scale_factor in 0.002 and
> > > autovacuum_analyze_scale_factor in 0.001
> >
> > The autovacuum scale factor has been twice the autoanalyze scale factor since the
> > beginning. You could search the archives from around 2004 for a reason, but I'd
> > say it might have to do with the fact that ANALYZE is much cheaper than VACUUM,
> > and that the impact of bad statistics is usually more severe than the impact of
> > some dead tuples.
> >
> > But there is no need for you to keep it that way when you change the parameters.
> > For example, if you want to speed up index only scans, you may want to set
> > "autovacuum_vacuum_scale_factor" to something like 0.01, but leave
> > "autovacuum_analyze_scale_factor" at the default value.
> >
> > The values that you suggest seem much too low - that will result in autovacuum
> > running all the time.
>
> Thanks for the information Laurenz Albe I have another question what will be effect
> if there are autovacuums running all the time, what will be settings you could suggest me for
> autovacuum_vacuum_scale_factor and autovacuum_analyze_scale_factor

Unless there are indications to choose different values, stick with the default
values of 0.1 and 0.2.

Yours,
Laurenz Albe
--
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