General Bug Report: GROUP BY with NULL not done properly(Oracle8 & DB/2 do this completely different)

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POSTGRESQL BUG REPORT TEMPLATE
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Your name :
Your email address : secret(at)kearneydev(dot)com

Category : runtime: back-end: SQL
Severity : non-critical

Summary: GROUP BY with NULL not done properly(Oracle8 & DB/2 do this completely different)

System Configuration
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Operating System : Linux 2.2.7 Redhat 5.2

PostgreSQL version : 6.4.2

Compiler used : 2.7.2.3

Hardware:
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Linux tau.kearneydev.com 2.2.7 #3 Thu Apr 29 10:10:41 EDT 1999 i686 unknown

Versions of other tools:
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Problem Description:
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The appearance of NULL in a table where a GROUP BY clause is
used causes the behavior of returning 1 line for every NULL.
Both Oracle8 and DB/2 perform this as I would expect. IE
a,b
1,1
1,2
NULL,1
NULL,2

SELECT a,sum(b) GROUP BY a returns on Postgres:
1,3
NULL,1
NULL,2

On Oracle8, DB/2, etc.:
1,3
NULL,3

Cut&paste from Oracle8:
SQL> select * from z;

A B
--------- ---------
1 1
1 2
5
10

SQL> select a,sum(b) from z group by a;

A SUM(B)
--------- ---------
1 3
15

SQL>

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Test Case:
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CREATE TABLE z(a int4,b int4);
INSERT INTO z values (1,2);
INSERT INTO z VALUES (1,1);
INSERT INTO z(b) VALUES (1);
INSERT INTO z(b) VALUES (2);
SELECT a,sum(b) FROM z GROUP BY a;

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Solution:
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For whatever reason I've observed many times that NULL<>NULL
under PostgreSQL, I've had to include many clauses in my
SQL statements to make up for this, perhaps if this was
corrected it would function properly.

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