DST prob for conversion from US/Eastern- GMT but not from GMT- US/Eastern.

Question

Hi folks,
I'm running the following SQL against a Oracle 10.2.0.1 g server using Oracle SqlDeveloper 1.5.3 & then again using SQLPlus 10.2.0.1.0.
I'm attempting to provide SQL that highlights the jump forward by one hour at 2am US/Eastern on 14th Mar 2010.
In order to do this I've converted times from GMT into US/Eastern using the oracle function from_tz and to_timestamp.
The following sql statements are suffixed with a 'correct' or 'incorrect' as to whether they correlate to what I would expect and indeed to the time returned from the World Clock website.
=======================
= Via Oracle SqlDeveloper 1.5.3
=======================
-- The first section of selects highlight the jump of 1 hour forward that occurs on the 14th of March 2010 by converting the GMT time to the corresponding US/Eastern time and the second block reverses the conversion.
select from_tz(to_timestamp('14-MAR-2010 0500' , 'DD-MON-YYYY HH24MI'), 'GMT') at time zone 'US/Eastern' from dual; -- returns 14-MAR-10 00:00:00.000000000 US/EASTERN correct
select from_tz(to_timestamp('14-MAR-2010 0600' , 'DD-MON-YYYY HH24MI'), 'GMT') at time zone 'US/Eastern' from dual; -- returns 14-MAR-10 01:00:00.000000000 US/EASTERN correct
select from_tz(to_timestamp('14-MAR-2010 0659' , 'DD-MON-YYYY HH24MI'), 'GMT') at time zone 'US/Eastern' from dual; -- returns 14-MAR-10 01:59:00.000000000 US/EASTERN correct
select from_tz(to_timestamp('14-MAR-2010 0700' , 'DD-MON-YYYY HH24MI'), 'GMT') at time zone 'US/Eastern' from dual; -- returns 14-MAR-10 03:00:00.000000000 US/EASTERN correct
select from_tz(to_timestamp('14-MAR-2010 0701' , 'DD-MON-YYYY HH24MI'), 'GMT') at time zone 'US/Eastern' from dual; -- returns 14-MAR-10 03:01:00.000000000 US/EASTERN correct
select from_tz(to_timestamp('14-MAR-2010 0800' , 'DD-MON-YYYY HH24MI'), 'GMT') at time zone 'US/Eastern' from dual; -- returns 14-MAR-10 04:00:00.000000000 US/EASTERN correct
select from_tz(to_timestamp('14-MAR-2010 0000' , 'DD-MON-YYYY HH24MI'), 'US/Eastern') at time zone 'GMT' from dual; -- returns 14-MAR-10 05:00:00.000000000 US/EASTERN correct
select from_tz(to_timestamp('14-MAR-2010 0100' , 'DD-MON-YYYY HH24MI'), 'US/Eastern') at time zone 'GMT' from dual; -- returns 14-MAR-10 06:00:00.000000000 US/EASTERN correct
select from_tz(to_timestamp('14-MAR-2010 0159' , 'DD-MON-YYYY HH24MI'), 'US/Eastern') at time zone 'GMT' from dual; -- returns 14-MAR-10 06:59:00.000000000 US/EASTERN correct
select from_tz(to_timestamp('14-MAR-2010 0200' , 'DD-MON-YYYY HH24MI'), 'US/Eastern') at time zone 'GMT' from dual; -- returns 14-MAR-10 07:00:00.000000000 US/EASTERN incorrect
select from_tz(to_timestamp('14-MAR-2010 0300' , 'DD-MON-YYYY HH24MI'), 'US/Eastern') at time zone 'GMT' from dual; -- returns 14-MAR-10 08:00:00.000000000 US/EASTERN incorrect
select from_tz(to_timestamp('14-MAR-2010 0301' , 'DD-MON-YYYY HH24MI'), 'US/Eastern') at time zone 'GMT' from dual; -- returns 14-MAR-10 08:01:00.000000000 US/EASTERN incorrect
select from_tz(to_timestamp('14-MAR-2010 0400' , 'DD-MON-YYYY HH24MI'), 'US/Eastern') at time zone 'GMT' from dual; -- returns 14-MAR-10 09:00:00.000000000 US/EASTERN incorrect
which is as I would expect. At 6:59am GMT the time in US/Eastern is 1:59 am, however, at 7:00am the time in US/Eastern is now 3:00am. This correlates to the times I get back when I perform the same calculations using the converter at the WorldClock.
http://www.timeanddate.com/worldclock/converter.html
However when I attempt to perform the same conversions except in reverse i.e. from US/Eastern to GMT I get different results.
-- everything is fine up until the actual time of the change over (2am US/Eastern). With the 2:00am time though I would expect Oracle or perhaps even the SqlDeveloper client to indicate either of the following :-
a) the time 14-MAR-10 02:00am US/Eastern is actually a non-existant time as per the WorldClock.
b) that it's defaulting the time 14-MAR-10 02:00am to 14-MAR-10 03:00am US/Eastern
instead the results proceeding the sql statements are output and for any time on/after 2am they are 1 hour behind their correct GMT times as per the world clock.
I understand that there is a patch for timezone's from 10.2.0.1 to 10.2.0.4 that should address this, however, the reason I'm posting this is because when I run the above SQL in sqlplus against the same server I get different results except this time both conversions are incorrect.
=======================
= Via SqlPlus 10.2.0.1.0
=======================
select from_tz(to_timestamp('14-MAR-2010 0500' , 'DD-MON-YYYY HH24MI'), 'GMT') at time zone 'US/Eastern' from dual; -- returns 14-MAR-10 00.00.00.000000000 US/EASTERN correct
select from_tz(to_timestamp('14-MAR-2010 0600' , 'DD-MON-YYYY HH24MI'), 'GMT') at time zone 'US/Eastern' from dual; -- returns 14-MAR-10 01.00.00.000000000 US/EASTERN correct
select from_tz(to_timestamp('14-MAR-2010 0659' , 'DD-MON-YYYY HH24MI'), 'GMT') at time zone 'US/Eastern' from dual; -- returns 14-MAR-10 01:59:00.000000000 US/EASTERN correct
select from_tz(to_timestamp('14-MAR-2010 0700' , 'DD-MON-YYYY HH24MI'), 'GMT') at time zone 'US/Eastern' from dual; -- returns 14-MAR-10 02.00.00.000000000 US/EASTERN incorrect
select from_tz(to_timestamp('14-MAR-2010 0701' , 'DD-MON-YYYY HH24MI'), 'GMT') at time zone 'US/Eastern' from dual; -- returns 14-MAR-10 03:01:00.000000000 US/EASTERN incorrect
select from_tz(to_timestamp('14-MAR-2010 0800' , 'DD-MON-YYYY HH24MI'), 'GMT') at time zone 'US/Eastern' from dual; -- returns 14-MAR-10 03.00.00.000000000 US/EASTERN incorrect
select from_tz(to_timestamp('13-MAR-2010 2300' , 'DD-MON-YYYY HH24MI'), 'US/Eastern') at time zone 'GMT' from dual; -- returns 14-MAR-10 04.00.00.000000000 GMT correct
select from_tz(to_timestamp('14-MAR-2010 0000' , 'DD-MON-YYYY HH24MI'), 'US/Eastern') at time zone 'GMT' from dual; -- returns 14-MAR-10 05.00.00.000000000 GMT correct
select from_tz(to_timestamp('14-MAR-2010 0100' , 'DD-MON-YYYY HH24MI'), 'US/Eastern') at time zone 'GMT' from dual; -- returns 14-MAR-10 06.00.00.000000000 GMT correct
select from_tz(to_timestamp('14-MAR-2010 0159' , 'DD-MON-YYYY HH24MI'), 'US/Eastern') at time zone 'GMT' from dual; -- returns 14-MAR-10 06.00.00.000000000 GMT correct
select from_tz(to_timestamp('14-MAR-2010 0200' , 'DD-MON-YYYY HH24MI'), 'US/Eastern') at time zone 'GMT' from dual; -- returns 14-MAR-10 07.00.00.000000000 GMT incorrect
select from_tz(to_timestamp('14-MAR-2010 0300' , 'DD-MON-YYYY HH24MI'), 'US/Eastern') at time zone 'GMT' from dual; -- returns 14-MAR-10 08.00.00.000000000 GMT incorrect
select from_tz(to_timestamp('14-MAR-2010 0301' , 'DD-MON-YYYY HH24MI'), 'US/Eastern') at time zone 'GMT' from dual; -- returns 14-MAR-10 08.01.00.000000000 GMT incorrect
select from_tz(to_timestamp('14-MAR-2010 0400' , 'DD-MON-YYYY HH24MI'), 'US/Eastern') at time zone 'GMT' from dual; -- returns 14-MAR-10 09.00.00.000000000 GMT incorrect
so it's as if the Oracle Client SqlDeveloper somehow intervenes as the results come back from the server an adjusts it for the first set of conversions but not the second.
Basically it looks like I need the patch for the timezones for 10.2.0.1 but what about the Clients? Is there patches I then need for them? Would the SqlPlus client that ships with 10.2.0.4 return the correct results or once the patch is applied to the server.
Has anyone else encountered this problem and if so would they be able to point me in the direction of a resource describing and resolving it?
Thanks,
Mark.

Answer 1

Hey Robert,
Yes indeed we are paying for Oracle support? As far as I know I logged in through metalink in an effort to investigate this problem.
Our DBA upgraded from 10.2.0.4 to 10.2.0.1 and all the inconsistency went away thankfully.
Thanks for taking the time to reply to me,
Mark.