timestamp arithmetic (a possible bug?)

Hi,

I saw this behaviour in PostgreSQL 7.2. (Once again, I know this is an old
release but I do not have a newer version installed, and I am only using
the server for research purposes). If you execute the following statement

SELECT (CAST('01.01.2004 10:01:00' AS TIMESTAMP) - CAST('01.01.2004
10:00:00' AS TIMESTAMP)) + CAST('01.01.2004 10:00:00' AS TIMESTAMP);

The result returned is:

      ?column?
---------------------
 2004-01-01 00:01:00
(1 row)

I was expecting: 2004-01-01 10:01:00.

Tried it on Oracle 8.0.5:

SELECT TO_DATE('01.01.2004 10:01:00', 'DD.MM.YYYY HH:MI:SS') -
TO_DATE('01.01.2004 10:00:00', 'DD.MM.YYYY HH:MI:SS') + TO_DATE('01.01.2004
10:00:00', 'DD.MM.YYYY HH:MI:SS') FROM DUAL;

---------------------------
2004-01-01 10:01:00
(1 row  selected)


And MSSQL 7:

SELECT (CAST('01.01.2004 10:01:00' AS DATETIME) - CAST('01.01.2004
10:00:00' AS DATETIME) + CAST('01.01.2004 10:00:00' AS DATETIME));


---------------------------

2004-01-01 10:01:00.000

(1 row(s) affected)


Is this a bug? Same thing happens if I use TimestampTZ rather than
Timestamp.

Best regards,

Ilir

____________________________________________

Ilir Gashi
PhD Student
Centre for Software Reliability
City University
Northampton Square, London EC1V 0HB
email: i.gashi@city.ac.uk
website: http://www.csr.city.ac.uk/csr_city/staff/gashi/
____________________________________________