[SQL] Problem with intervals

[Bob Smith]

I'm getting an unexpected result using intervals in an expression:

select ('2003-10-26 0:00:00'::timestamp + '1 day'::interval)::date;
date

 2003-10-26
(1 row)
When I get rid of the date cast it becomes clear what is happening:

select '2003-10-26 0:00:00'::timestamp + '1 day'::interval;
?column?

 2003-10-26 23:00:00-08
(1 row)
I assumed '1 day' would always increment the date by 1, but it appears 
that '1 day' just means '24 hours', and due to the daylight/standard 
time shift, October 26 was 25 hours long this year.

Is this a Postgres bug, or is this correct SQL behavior?  I'm running 
Postgres 7.2.2.

Bob S.

---(end of broadcast)---
TIP 2: you can get off all lists at once with the unregister command
   (send "unregister YourEmailAddressHere" to [EMAIL PROTECTED])

Re: [SQL] Problem with intervals

[Bob Smith]

On Tuesday, Dec 2, 2003, at 03:53 US/Pacific, Alexander M. Pravking 
wrote:

On Mon, Dec 01, 2003 at 09:09:20PM -0800, Bob Smith wrote:
I'm getting an unexpected result using intervals in an expression:

select ('2003-10-26 0:00:00'::timestamp + '1 day'::interval)::date;
date

 2003-10-26
(1 row)
Try using '2003-10-26 0:00:00'::date + 1;
integers do not lie ;-)
Aha!  That solves my problem for now.  I had also discovered that using 
'25 hours'::interval works, but the integer approach is better.

It has been discussed several times, Tom Lane offered to add 'day' as
a separate interval unit (like 'second' and 'month' at this moment),
but noone took a shot at it, AFAIK.
Note also, that in 7.3 "timestamp" means "timestamp without time zone",
while in 7.2 it's "timestamp with time zone".
Yet another reason to upgrade, I guess I'm gonna have to do it soon...

Thanks for your help!

Bob S.

---(end of broadcast)---
TIP 2: you can get off all lists at once with the unregister command
   (send "unregister YourEmailAddressHere" to [EMAIL PROTECTED])