Is this proper UNION behavior??

According to my copy of SQL For Smarties by Joe Celko (2nd ed, p. 411):

> The UNION removes all duplicate rows from the results and does
> not care from which table the duplicate rows came.  We could
> use this feature to write a query to remove duplicates from a
> table:
>    (TABLE tableA)
>    UNION
>    (TABLE tableA);
>
> But this is the same as
>    SELECT DISTINCT * FROM tableA;

however, per the below example, the union and the select distinct
are not the same in postgres 7.0.2.  is joe missing somehting here?
or am i?

thanks
--e--


CREATE TABLE "has_some_dupes" (
        "a_col" character(3),
        "b_col" character(3),
        "c_col" character(3)
);
COPY "has_some_dupes" FROM stdin;
abc     def     ghi
abc     def     ghi
abc     def     ghi
jkl     mno     pqr
jkl     mno     pqr
jkl     mno     pqr
stu     vwx     yz
stu     vwx     yz
stu     vwx     yz
\.


ebridges=> (select * from has_some_dupes)
ebridges-> UNION
ebridges-> (select * from has_some_dupes);
 a_col | b_col | c_col
-------+-------+-------
 abc   | def   | ghi
 abc   | def   | ghi
 abc   | def   | ghi
 jkl   | mno   | pqr
 jkl   | mno   | pqr
 jkl   | mno   | pqr
 stu   | vwx   | yz
 stu   | vwx   | yz
 stu   | vwx   | yz
(9 rows)


ebridges=> select distinct * from has_some_dupes;
 a_col | b_col | c_col
-------+-------+-------
 abc   | def   | ghi
 jkl   | mno   | pqr
 stu   | vwx   | yz
(3 rows)