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	Mon, 21 Aug 2023 18:07:54 -0400
Date: Mon, 21 Aug 2023 18:07:54 -0400
From: Bruce Momjian <bruce@momjian.us>
To: Erwin Brandstetter <brsaweda@gmail.com>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>,
	David Rowley <drowley@postgresql.org>
Subject: Re: PG 16 draft release notes ready
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On Sat, Aug 19, 2023 at 04:24:48AM +0200, Erwin Brandstetter wrote:
> I posted to pgsql-docs first, but was kindly redirected here by Jonathan:
> 
> The release notes for Postgres 16 says here:
> https://www.postgresql.org/docs/16/release-16.html#RELEASE-16-PERFORMANCE
> 
> Same as here:
> https://momjian.us/pgsql_docs/release-16.html#RELEASE-16-PERFORMANCE
> 
>     Allow window functions to use ROWS mode internally when RANGE mode is
> specified but unnecessary (David Rowley)

Yes, I didn't like "specified" myself but never returned to improve it. 
I am now using:

	Allow window functions to use the faster <link
	linkend="syntax-window-functions"><literal>ROWS</literal></link> mode
	internally when <literal>RANGE</literal> mode is active but unnecessary
	                                                 ------
	(David Rowley)

Can that be improved?

> But the improvement (fix to some degree) also applies to the much more common
> case where no mode has been specified, RANGE unfortunately being the default.
> That includes the most common use case "row_number() OVER (ORDER BY col)",
> where RANGE mode should not be applied to begin with, according to SQL specs.
> This is what made me investigate, test and eventually propose a fix in the
> first place. See:

Yes, very true.

> Also, I was hoping to be mentioned in the release note for working this out:
> 
>     Allow window functions to use the faster ROWS mode internally when RANGE
> mode is specified or would be default, but unnecessary (David Rowley, Erwin
> Brandstetter)

Uh, I have CC'ed David Rowley because that is unclear based on the
commit message.  I don't normally mention reviewers.

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

  Only you can decide what is important to you.