From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
cc: Peter Geoghegan <pg@bowt.ie>, ro b <bigbro_wq@hotmail.com>,
        pgsql-hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: Self contradictory examining on rel's baserestrictinfo
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Comments: In-reply-to Robert Haas <robertmhaas@gmail.com>
	message dated "Tue, 26 Nov 2024 11:55:29 -0500"
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Date: Tue, 26 Nov 2024 12:13:55 -0500
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Robert Haas <robertmhaas@gmail.com> writes:
> On Mon, Nov 25, 2024 at 4:39=E2=80=AFPM Tom Lane <tgl@sss.pgh.pa.us> wro=
te:
>> ...  I think Robert
>> must have had constraint_exclusion =3D on for his examples a
>> couple messages back.)

> I definitely didn't change the value of that setting. It's possible I
> was running on an older branch, but I don't think it was anything
> ancient.

Hmm, constraint_exclusion has defaulted to "partition" for many
years now.  But when I tried to reproduce your examples at [1]:

regression=3D# create table foo (a int);
CREATE TABLE
regression=3D# explain select * from foo where a < 1 and a > 1;
                     QUERY PLAN                      =

-----------------------------------------------------
 Seq Scan on foo  (cost=3D0.00..48.25 rows=3D13 width=3D4)
   Filter: ((a < 1) AND (a > 1))
(2 rows)

regression=3D# show constraint_exclusion;
 constraint_exclusion =

----------------------
 partition
(1 row)

regression=3D# set constraint_exclusion =3D on;
SET
regression=3D# explain select * from foo where a < 1 and a > 1;
                QUERY PLAN                =

------------------------------------------
 Result  (cost=3D0.00..0.00 rows=3D0 width=3D0)
   One-Time Filter: false
(2 rows)

and similarly for some of the other examples (I didn't try
every one).  Maybe your test table was partitioned??

			regards, tom lane

[1] https://www.postgresql.org/message-id/CA%2BTgmoZqiCwHbZczXXLjucfuHi%3D=
7EahSyzEj5yrqYKMQ0QOL9Q%40mail.gmail.com