On Wed, Nov 18, 2009 at 11:18 PM, Andrew Gierth
<andrew@tao11.riddles.org.uk> wrote:
>>>>>> "Kevin" == "Kevin Grittner" <Kevin.Grittner@wicourts.gov> writes:
>
> >> If he meant (A), then you store the event as:
> >> (ts,tz) = (timestamp '2010-07-27 10:30:00',
> >> 'Chile/Santiago')
>
> >> If he meant (B), then you store the event as
> >> (tsz,tz) = (timestamp '2010-07-27 10:30:00' at time zone
> >> 'Chile/Santiago', 'Chile/Santiago')
>
> Kevin> You seem to be agreeing that these problems can't be solved
> Kevin> without storing a time zone string in addition to the
> Kevin> timestamp. As I read it, Hernán was wishing for types which
> Kevin> include this, rather than having to do the above dance with
> Kevin> multiple values.
>
> Right, but including more data in a single type is the wrong approach,
> since it complicates the semantics and interferes with normalization.
> For example, if you have a type T which incorporates a timestamp and a
> timezone, what semantics does the T = T operator have? What semantics
> apply if the definitions of timezones change? What if you're storing
> times of events at specific places; in that case you want to associate
> the timezone with the _place_ not the event (so that if the timezone
> rules change, moving the place from one timezone to another, you only
> have to change the place, not all the events that refer to it).
Also, if someone DOES want to use these together, isn't that what
composite types are for?
...Robert