From: Hans Buschmann <buschmann@nidsa.net>
To: "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>,
	Tom Lane <tgl@sss.pgh.pa.us>
Subject: Re: Making Vars outer-join aware
Thread-Topic: Making Vars outer-join aware
Thread-Index: AQHZL9jYsrLdnKDgv0e6Yna44D71cg==
Date: Tue, 24 Jan 2023 10:11:00 +0000
Message-ID: <8c3a9f69b5d44373bdd35e640e59305c@nidsa.net>
Accept-Language: de-DE, en-US
Content-Language: de-DE
Content-Type: multipart/alternative;
	boundary="_000_8c3a9f69b5d44373bdd35e640e59305cnidsanet_"
MIME-Version: 1.0
Archived-At: 
 <https://www.postgresql.org/message-id/8c3a9f69b5d44373bdd35e640e59305c%40nidsa.net>
Precedence: bulk

--_000_8c3a9f69b5d44373bdd35e640e59305cnidsanet_
Content-Type: text/plain; charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable

Hello Tom


I just noticed your new efforts in this area.


I wanted to recurr to my old thread [1] considering constant propagation of=
 quals.


You gave an elaborated explanation at that time, but my knowledge was/is no=
t yet sufficient to reveil the technical details.


In our application the described method is widespread used with much succes=
s (now at pg15.1 Fedora), but for unexperienced SQL authors this is not rea=
lly obviously to choose (i.e. using the explicit constant xx_season=3D3 as =
qual). This always requires a "Macro" processor to compose the queries (in =
my case php) and a lot of programmer effort in the source code.


I can't review/understand your patchset for the planner, but since it cover=
s the same area, the beformentioned optimization could perhaps be addressed=
 too.


With respect of the nullability of these quals I immediately changed all of=
 them to NOT NULL, which seems the most natural way when these quals are al=
so used for partioning.


[1]  https://www.postgresql.org/message-id/1571413123735.26467@nidsa.net


Thanks for looking


Hans Buschmann


--_000_8c3a9f69b5d44373bdd35e640e59305cnidsanet_
Content-Type: text/html; charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable

<html>
<head>
<meta http-equiv=3D"Content-Type" content=3D"text/html; charset=3Diso-8859-=
1">
<style type=3D"text/css" style=3D"display:none;"><!-- P {margin-top:0;margi=
n-bottom:0;} --></style>
</head>
<body dir=3D"ltr">
<div id=3D"divtagdefaultwrapper" style=3D"font-size:12pt;color:#000000;font=
-family:Calibri,Arial,Helvetica,sans-serif;">
<p>Hello Tom</p>
<p><br>
</p>
<p>I just noticed your new efforts in this area.</p>
<p><br>
</p>
<p>I wanted to recurr to my old thread [1] considering constant propagation=
 of quals.</p>
<p><br>
</p>
<p>You gave an elaborated explanation at that time, but my knowledge was/is=
 not yet sufficient to reveil the technical details.</p>
<p><br>
</p>
<p>In our application the described method is widespread used with much suc=
cess (now at pg15.1 Fedora), but for unexperienced SQL authors this is not =
really obviously to choose (i.e.&nbsp;using the explicit constant xx_season=
=3D3 as qual). This always requires a &quot;Macro&quot;
 processor to compose the queries (in my case php) and a lot of programmer =
effort in the source code.</p>
<p><br>
</p>
<p>I can't review/understand your patchset for the planner, but since it co=
vers the same area, the beformentioned optimization could perhaps be addres=
sed too.</p>
<p><br>
</p>
<p>With respect of the nullability of these quals I immediately changed&nbs=
p;all of them&nbsp;to NOT NULL, which seems the most natural way when these=
 quals are also used for partioning.</p>
<p><br>
</p>
<p>[1]&nbsp;&nbsp;<a href=3D"https://www.postgresql.org/message-id/15714131=
23735.26467@nidsa.net" class=3D"OWAAutoLink" id=3D"LPlnk794464" previewremo=
ved=3D"true">https://www.postgresql.org/message-id/1571413123735.26467@nids=
a.net</a></p>
<p><br>
</p>
<p>Thanks for looking</p>
<p><br>
</p>
<p>Hans Buschmann</p>
<p><br>
</p>
</div>
</body>
</html>

--_000_8c3a9f69b5d44373bdd35e640e59305cnidsanet_--