From: | Michael Fuhr <mike(at)fuhr(dot)org> |
---|---|
To: | Klint Gore <kg(at)kgb(dot)une(dot)edu(dot)au> |
Cc: | Russell Smith <mr-russ(at)pws(dot)com(dot)au>, pgsql-bugs(at)postgresql(dot)org, Nicholas <hb(at)x256(dot)com> |
Subject: | Re: BUG #1993: Adding/subtracting negative time intervals |
Date: | 2005-10-25 03:38:26 |
Message-ID: | 20051025033826.GA33218@winnie.fuhr.org |
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Lists: | pgsql-bugs pgsql-hackers |
On Tue, Oct 25, 2005 at 12:48:10PM +1000, Klint Gore wrote:
> On Tue, 25 Oct 2005 08:51:59 +1000, Russell Smith <mr-russ(at)pws(dot)com(dot)au> wrote:
> > Looks to mee like Daylight Savings has conveniently started.
>
> But the elapsed time for those results is only 6 days, 23 hours.
>
> That's changed since v7.4.7
I think this item in the 8.1 Release Notes might be relevant:
* Add an internal day field to INTERVAL so a one day interval can be
distinguished from a 24 hour interval (Michael Glaesemann)
Days that contain a daylight savings time adjustment are not 24 hours,
but typically 23 or 25 hours. This change allows days (not fixed
24-hour periods) to be added to dates who's result includes a daylight
savings time adjustment period. Therefore, while in previous releases
1 day and 24 hours were interchangeable interval values, in this
release they are treated differently, e.g.
'2005-05-03 00:00:00 EST' + '1 day' = '2005-05-04 00:00:00-04'
'2005-05-03 00:00:00 EST' + '24 hours' = '2005-05-04 01:00:00-04'
Here's an example and the results from 7.4.9, 8.0.4, and 8.1beta4:
\x
SET TimeZone TO 'Australia/NSW';
SELECT version(), now(), now() + interval'1 week', now() + interval'168 hours';
-[ RECORD 1 ]-----------------------------------------------------------------------
version | PostgreSQL 7.4.9 on sparc-sun-solaris2.9, compiled by GCC gcc (GCC) 3.4.2
now | 2005-10-25 13:35:43.663169+10
?column? | 2005-11-01 14:35:43.663169+11
?column? | 2005-11-01 14:35:43.663169+11
-[ RECORD 1 ]-----------------------------------------------------------------------
version | PostgreSQL 8.0.4 on sparc-sun-solaris2.9, compiled by GCC gcc (GCC) 3.4.2
now | 2005-10-25 13:35:45.459081+10
?column? | 2005-11-01 14:35:45.459081+11
?column? | 2005-11-01 14:35:45.459081+11
-[ RECORD 1 ]--------------------------------------------------------------------------
version | PostgreSQL 8.1beta4 on sparc-sun-solaris2.9, compiled by GCC gcc (GCC) 3.4.2
now | 2005-10-25 13:35:47.104595+10
?column? | 2005-11-01 13:35:47.104595+11
?column? | 2005-11-01 14:35:47.104595+11
--
Michael Fuhr
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