Re: PG 14 release notes, first draft

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(at)momjian(dot)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(at)bowt(dot)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