Date: Tue, 18 May 2021 09:44:09 -0500
From: Justin Pryzby <pryzby@telsasoft.com>
To: Bruce Momjian <bruce@momjian.us>
Cc: Masahiko Sawada <sawada.mshk@gmail.com>, pgsql-hackers@postgresql.org,
	Peter Geoghegan <pg@bowt.ie>
Subject: Re: PG 14 release notes, first draft
Message-ID: <20210518144409.GL373@telsasoft.com>
References: <20210510060308.GC6088@momjian.us>
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 <20210518140725.GA30270@momjian.us>
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On Tue, May 18, 2021 at 10:07:25AM -0400, Bruce Momjian wrote:
> On Tue, May 18, 2021 at 06:28:49PM +0900, Masahiko Sawada wrote:
> > On Mon, May 10, 2021 at 3:03 PM Bruce Momjian <bruce@momjian.us> wrote:
> > >
> > > I have committed the first draft of the PG 14 release notes.  You can
> > > see the most current  build of them here:
> > >
> > >         https://momjian.us/pgsql_docs/release-14.html
> > 
> > I think we need to mention in the release note that
> > vacuum_cleanup_index_scale_factor GUC parameter has been removed and
> > vacuum_cleanup_index_scale_factor storage parameter has been
> > deprecated (please refer to commit 9f3665fb and effdd3f3b63).
> 
> Looking at the full commit message:
> 
> 	commit 9f3665fbfc
> 	Author: Peter Geoghegan <pg@bowt.ie>
> 	Date:   Wed Mar 10 16:27:01 2021 -0800
> 	
> 	    Don't consider newly inserted tuples in nbtree VACUUM.
> 	
> 	    Remove the entire idea of "stale stats" within nbtree VACUUM (stop
> 	    caring about stats involving the number of inserted tuples).  Also
> 	    remove the vacuum_cleanup_index_scale_factor GUC/param on the master
> 	    branch (though just disable them on postgres 13).

> This was backpatched into PG 13.3, which was released last week:

> 	      remove the stale-statistics logic.  The control parameter for that,
> 	      <varname>vacuum_cleanup_index_scale_factor</varname>, will be
> 	      removed entirely in v14.  In v13, it remains present to avoid
> 	      breaking existing configuration files, but it no longer does
> 	      anything.
> 	     </para>
> 	    </listitem>
> 
> Therefore, it didn't show up in my src/tools/git_changelog output, and I
> did not include it.

Normally, stuff that was backpatched isn't included in major release notes,
since the change would/could normally happen during a minor -> minor+1 release.

As things stand, in this case I think it *should* be included, since the
backpatched change isn't the same as the change to HEAD (removing the GUC).
The git_changelog output might well be wrong in this case (or, arguably, the
"remove the GUC entirely" should've been a separate master-only commit than the
"make the GUC do nothing" commit).

However, Peter indicated an intent to add a reloption to disable the vacuum
optimization, so maybe the removal of the GUC could be documented at that time.

-- 
Justin