Hi Tom,
this seems a serious bug:
testdb=>
testdb=> create table t1(a int, b text);
CREATE TABLE
testdb=> create table t2(a int, b text);
CREATE TABLE
testdb=> insert into t1 values(1,'pippo');
INSERT 7591667 1
testdb=> insert into t1 values(2,'pluto');
INSERT 7591668 1
testdb=> insert into t2 values(3,'paperino');
INSERT 7591669 1
testdb=> insert into t2 values(3,'paperino');
INSERT 7591670 1
select a,b from t1 union (select a,b from t2);
a | b
---+----------
1 | pippo
2 | pluto
3 | paperino
(3 rows)
Wrong ! The query should return 4 rows. In other words i don't know
why postgres performs the following query:
select a,b from t1 union (select DISTINCT a,b from t2);
instead of the required one.
I think i's a bug.
Thank you.
Silvio Scarpati
