On Mon, Nov 01, 2004 at 11:00:10AM -0500, Tom Lane wrote: > David Garamond <[EMAIL PROTECTED]> writes: > > So the question remains, does AT TIME ZONE already do > > what it's supposed to do (according to SQL standard, that is) > > It does not really. By my reading of SQL99, the result should always be > timestamptz, and the behavior when the input is already timestamptz > should be that the new timezone spec is inserted while preserving the > same absolute time (UTC-equivalent timestamp).
That's quite a different use of timestamptz. Does the SQL standard decide what defines a timestamp with a timezone, does it only allow the 'number of hours relative to UTC' or does it also allow different places in the world. > Certainly not. We can't have timestamptz values that are in fact distinct > comparing as equal. My guess is that the sort order for timestamptz > should be UTC-equivalent time as major sort key, with equal UTC times > sorted somehow on their timezone specs. That's an interesting one, Is Australia/Sydney before or after Australia/Brisbane. It is questionable if there is any meaningful order to timezones. Alphabetical will make no-one happy, by longatude/latitude is way too complex. Maybe base offset, then alphabetical. It's a backward incompatable change (or is it?), and the current result is useful in a sense... -- Martijn van Oosterhout <[EMAIL PROTECTED]> http://svana.org/kleptog/ > Patent. n. Genius is 5% inspiration and 95% perspiration. A patent is a > tool for doing 5% of the work and then sitting around waiting for someone > else to do the other 95% so you can sue them.
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