Date: Mon, 11 May 2020 21:06:14 -0400
From: Bruce Momjian <bruce@momjian.us>
To: Justin Pryzby <pryzby@telsasoft.com>
Cc: Amit Kapila <amit.kapila16@gmail.com>,
	PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: PG 13 release notes, first draft
Message-ID: <20200512010614.GO4666@momjian.us>
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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.

-- 
  Bruce Momjian  <bruce@momjian.us>        https://momjian.us
  EnterpriseDB                             https://enterprisedb.com

+ As you are, so once was I.  As I am, so you will be. +
+                      Ancient Roman grave inscription +