On Fri, Jul 15, 2005 at 09:59:27AM -0400, Tom Lane wrote:
> Luca Pireddu <luca@cs.ualberta.ca> writes:
> > So, am I wrong in expecting each strain record to appear only once in the
> > result set? Or is there something wrong with PostgreSQL?
>
> Could we see a self-contained example (table definitions and sample data
> as a SQL script)? I don't really have time to reverse-engineer a test
> case from your description ...
I've been reverse-engineering and simplifying this. Here's something
that I think is close:
CREATE TABLE foo (id integer);
CREATE TABLE bar (id1 integer, id2 integer);
INSERT INTO foo VALUES (1);
INSERT INTO bar VALUES (1, 1);
INSERT INTO bar VALUES (2, 2);
INSERT INTO bar VALUES (3, 1);
SELECT *
FROM foo
WHERE id IN (SELECT id2 FROM (SELECT DISTINCT id1, id2 FROM bar) AS s);id
---- 1 1
(2 rows)
SELECT *
FROM foo
WHERE id IN (SELECT id2 FROM (SELECT id1, id2 FROM bar) AS s);id
---- 1
(1 row)
8.0.3 and HEAD behave as shown. 7.4.8, 7.3.10, and 7.2.8 return a
single row for both queries.
--
Michael Fuhr
http://www.fuhr.org/~mfuhr/
