Date: Thu, 21 Mar 2024 18:01:00 -0400
From: Bruce Momjian <bruce@momjian.us>
To: "Fujii.Yuki@df.MitsubishiElectric.co.jp" <Fujii.Yuki@df.mitsubishielectric.co.jp>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Robert Haas <robertmhaas@gmail.com>,
	PostgreSQL-development <pgsql-hackers@postgresql.org>,
	Alexander Pyhalov <a.pyhalov@postgrespro.ru>,
	Stephen Frost <sfrost@snowman.net>,
	"Finnerty, Jim" <jfinnert@amazon.com>,
	Andres Freund <andres@anarazel.de>,
	Tomas Vondra <tomas.vondra@enterprisedb.com>,
	Julien Rouhaud <rjuju123@gmail.com>,
	Daniel Gustafsson <daniel@yesql.se>,
	vignesh C <vignesh21@gmail.com>
Subject: Re: Partial aggregates pushdown
Message-ID: <ZfyuHBAA6eZO7cxq@momjian.us>
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On Thu, Mar 21, 2024 at 11:37:50AM +0000, Fujii.Yuki@df.MitsubishiElectric.co.jp wrote:
> Hi. Mr.Momjian, Mr.Lane, Mr.Haas, hackers.
> 
> I apologize for any misunderstanding regarding the context of the attached patch and
> the points on which I requested a review. Could you please allow me to clarify?
> 
> In the review around early December 2023, I received the following three issues pointed out by Mr.Haas[1].
> 1. Transmitting state value safely between machines
> 2. Making the patch clearer by adding SQL keywords
> 3. Fixing the behavior when the HAVING clause is present
> 
> In the email sent on February 22, 2024[2], I provided an update on the progress made in addressing these issues.
> Regarding issue 1, I have only provided a proposed solution in the email and have not started the programming. 
> Therefore, the latest patch is not in a commit-ready state. As mentioned later, we have also temporarily reverted the changes made to the documentation.
> Before proceeding with the programming, I would like to discuss the proposed solution with the community and seek consensus.
> If it is necessary to have source code in order to discuss, I can create a simple prototype so that I can receive your feedback.
> Would you be able to provide your opinions on it?
> 
> Regarding issue 2., I have confirmed that creating a prototype allows us to address the issue and clear the patch.
> In this prototype creation, the main purpose was to verify if the patch can be cleared and significant revisions were made to the previous version.
> Therefore, I have removed all the document differences.
> I have submitted a patch [3] that includes the fixes for issue 3. to the patch that was posted in [2].
> Regarding the proposed solution for issue 1, unlike the patch posted in [3], 
> we have a policy of not performing partial aggregation pushdown if we cannot guarantee compatibility and safety.
> The latest patch in [3] is a POC patch. The patch that Mr. Momjian reviewed is this.
> If user-facing documentation is needed for this POC patch, it can be added.
> 
> I apologize for the lack of explanation regarding this positioning, which may have caused misunderstandings regarding the patch posted in [3].

That makes sense.  Let's get you answers to those questions first before
you continue.

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

  Only you can decide what is important to you.