From: "Fujii.Yuki@df.MitsubishiElectric.co.jp"
	<Fujii.Yuki@df.MitsubishiElectric.co.jp>
To: Bruce Momjian <bruce@momjian.us>, Tom Lane <tgl@sss.pgh.pa.us>, Robert
 Haas <robertmhaas@gmail.com>, PostgreSQL-development
	<pgsql-hackers@postgresql.org>
CC: 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>, "Fujii.Yuki@df.MitsubishiElectric.co.jp"
	<Fujii.Yuki@df.MitsubishiElectric.co.jp>
Subject: RE: Partial aggregates pushdown
Thread-Topic: Partial aggregates pushdown
Thread-Index:
 AQHaZV+FhOOC+4jqD0O6QaSNENpP/LEfzV+AgBnxJJCABe8WAIAAEJqAgAAb+QCAAj/F8A==
Date: Thu, 21 Mar 2024 11:37:50 +0000
Deferred-Delivery: Thu, 21 Mar 2024 11:36:51 +0000
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Precedence: bulk

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 clar=
ify?

In the review around early December 2023, I received the following three is=
sues 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 prog=
ress made in addressing these issues.
Regarding issue 1, I have only provided a proposed solution in the email an=
d have not started the programming.=20
Therefore, the latest patch is not in a commit-ready state. As mentioned la=
ter, we have also temporarily reverted the changes made to the documentatio=
n.
Before proceeding with the programming, I would like to discuss the propose=
d 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 pa=
tch that was posted in [2].
Regarding the proposed solution for issue 1, unlike the patch posted in [3]=
,=20
we have a policy of not performing partial aggregation pushdown if we canno=
t 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 m=
ay have caused misunderstandings regarding the patch posted in [3].

[1] https://www.postgresql.org/message-id/CA%2BTgmoYCrtOvk2f32qQKZV%3DjNL35=
tandf2A2Dp_2F5ASuiG1BA%40mail.gmail.com
[2] https://www.postgresql.org/message-id/TYAPR01MB5514F0CBD9CD4F84A2611981=
95562%40TYAPR01MB5514.jpnprd01.prod.outlook.com
[3] https://www.postgresql.org/message-id/TYAPR01MB55141D18188AC86ADCE35FCB=
952F2%40TYAPR01MB5514.jpnprd01.prod.outlook.com

Sincerely yours,
Yuuki Fujii

--
Yuuki Fujii
Information Technology R&D Center Mitsubishi Electric Corporation