On Tue, May 12, 2020 at 6:36 AM Bruce Momjian <bruce@momjian.us> wrote:
>
> On Mon, May 11, 2020 at 07:41:55PM -0500, Justin Pryzby wrote:
> > On Mon, May 11, 2020 at 10:52:41AM +0530, Amit Kapila wrote:
> > > One more observation:
> > >
> > > Allow inserts to trigger autovacuum activity (Laurenz Albe, Darafei
> > > Praliaskouski)
> > > This new behavior allows pages to be set as all-visible, which then
> > > allows index-only scans, ...
> >
> > > The above sentence sounds to mean that this feature allows index-only
> > > scans in more number of cases after this feature. Is that what you
> > > intend to say? If so, is that correct? Because I think this will
> > > allow index-only scans to skip "Heap Fetches" in more cases.
> >
> > I think what you mean is that the autovacuum feature, in addition to
> > encouraging the *planner* to choose an indexonly scan, will *also* allow (at
> > execution time) fewer heap fetches for a plan which would have
> > already/previously used IOS. Right ? So maybe it should say "allows OR
> > IMPROVES index-only scans" or "allows plans which use IOS to run more
> > efficiently".
>
> Yes, I see your point now. New text is:
>
> This new behavior reduces the work necessary when the table
> needs to be frozen and allows pages to be set as all-visible.
> All-visible pages allow index-only scans to access fewer heap rows.
>
The next text LGTM. Thanks.
--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com