Re: Timezones (in 8.5?)

On Wed, Nov 18, 2009 at 11:18 PM, Andrew Gierth
<andrew(at)tao11(dot)riddles(dot)org(dot)uk> wrote:
>>>>>> "Kevin" == "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)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