"Kevin Grittner" <Kevin.Grittner@wicourts.gov> writes:
> It's been a while since I looked at it, but my recollection is that
> much of the standard date/time math which people assert can't handle
> practical use cases do work if the timestamps and times WITH TIME
> ZONE have a time zone in the offset-from-UTC format.
Certainly --- as long as you are considering a fixed UTC offset, the
standard does what it claims to. The knock on it is that in the real
world people want sane behavior with real-world timezone definitions
that have non-constant UTC offsets.
As an example, timestamptz '2007-01-01 00:00 -05' + interval '6 months'
must yield 2007-07-01 00:00 -05 according to the spec, AFAICS; but most
people living in the EST5EDT zone would prefer to get midnight -04.
There are probably some folk in South America who'd prefer midnight
-06. (Looks at a map ... hm, maybe not, but certainly Europe vs
Africa would produce some such examples.)
regards, tom lane