Re: Eagerly scan all-visible pages to amortize aggressive vacuum

On Mon, Feb 3, 2025 at 9:09 PM Andres Freund <andres@anarazel.de> wrote:
> > +     <varlistentry id="guc-vacuum-max-eager-freeze-failure-rate" xreflabel="vacuum_max_eager_freeze_failure_rate">
> > +      <term><varname>vacuum_max_eager_freeze_failure_rate</varname> (<type>floating point</type>)
> > +      <indexterm>
> > +       <primary><varname>vacuum_max_eager_freeze_failure_rate</varname> configuration parameter</primary>
> > +      </indexterm>
> > +      </term>
> > +      <listitem>
> > +       <para>
> > +        Specifies the maximum fraction of pages that
> > +        <command>VACUUM</command> may scan and <emphasis>fail</emphasis> to set
> > +        all-frozen in the visibility map before disabling eager scanning. A
> > +        value of <literal>0</literal> disables eager scanning altogether. The
> > +        default is <literal>0.03</literal> (3%).
> > +       </para>
>
> Fraction of what?

"pages", according to the text.

I'm not really sure what you think is wrong with this. There may be an
even better way to explain this but this doesn't seem bad to me.

--
Robert Haas
EDB: http://www.enterprisedb.com