Date: Sun, 5 Mar 2023 18:45:38 +0000 (UTC)
From: "Howard A. Chou" <maingroup@yahoo.com>
To: "pgsql-bugs@lists.postgresql.org" <pgsql-bugs@lists.postgresql.org>
Message-ID: <382692025.2538273.1678041938275@mail.yahoo.com>
Subject: found a possible bug, modulus of an integer on a partition table
 appears to be wrong
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postgres@osboxes:~/pgdata1$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:=C2=A0 =C2=A0 Ubuntu 22.04 LTS
Release:=C2=A0 =C2=A0 =C2=A0 =C2=A0 22.04
Codename:=C2=A0 =C2=A0 =C2=A0 =C2=A0jammy
postgres@osboxes:~/pgdata1$


psql (14.2 (Ubuntu 14.2-1ubuntu1))
Type "help" for help.


postgres=3D# \x
Expanded display is on.
postgres=3D# select version();
-[ RECORD 1 ]--------------------------------------------------------------=
------------------------------------------------------
version | PostgreSQL 14.2 (Ubuntu 14.2-1ubuntu1) on x86_64-pc-linux-gnu, co=
mpiled by gcc (Ubuntu 11.2.0-19ubuntu1) 11.2.0, 64-bit


postgres=3D#


postgres=3D# create table t1 (c1 int) partition by hash (c1);
CREATE TABLE
postgres=3D# create table t1_0 partition of t1 for values with (modulus 2, =
remainder 0);
CREATE TABLE
postgres=3D# create table t1_1 partition of t1 for values with (modulus 2, =
remainder 1);
CREATE TABLE
postgres=3D# \dt
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 List of relations
=C2=A0Schema | Name |=C2=A0 =C2=A0 =C2=A0 =C2=A0Type=C2=A0 =C2=A0 =C2=A0 =
=C2=A0 |=C2=A0 Owner
--------+------+-------------------+----------
=C2=A0public | t1=C2=A0 =C2=A0| partitioned table | postgres
=C2=A0public | t1_0 | table=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0=
| postgres
=C2=A0public | t1_1 | table=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0=
| postgres
(3 rows)


postgres=3D# insert into t1 values (4),(6), (8);
INSERT 0 3
postgres=3D# select * from t1_0;
=C2=A0c1
----
(0 rows)


postgres=3D# select * from t1_1;
=C2=A0c1
----
=C2=A0 4
=C2=A0 6
=C2=A0 8
(3 rows)


postgres=3D# select 4 % 2, 6 % 2, 8 % 2;
=C2=A0?column? | ?column? | ?column?
----------+----------+----------
=C2=A0 =C2=A0 =C2=A0 =C2=A0 0 |=C2=A0 =C2=A0 =C2=A0 =C2=A0 0 |=C2=A0 =C2=A0=
 =C2=A0 =C2=A0 0
(1 row)


The remainder of 4, 6, 8 mod 2 should be 0.=C2=A0 Instead of inserting into=
 t1_0, all values were inserted into t1_1

Thanks,

Howard A Chou