Re: AT TIME ZONE: "convert"?
От | Bruce Momjian |
---|---|
Тема | Re: AT TIME ZONE: "convert"? |
Дата | |
Msg-id | 200411280512.iAS5COu14073@candle.pha.pa.us обсуждение исходный текст |
Ответ на | Re: AT TIME ZONE: "convert"? (Tom Lane <tgl@sss.pgh.pa.us>) |
Список | pgsql-general |
Added TODO description: * Allow TIMESTAMP WITH TIME ZONE to store the original timezone information, either zone name or offset from UTC If the TIMESTAMP value is stored with a time zone name, interval computations should adjust based on the time zone rules, e.g. adding 24 hours to a timestamp would yield a different result from adding one day. --------------------------------------------------------------------------- Tom Lane wrote: > Martijn van Oosterhout <kleptog@svana.org> writes: > > On Mon, Nov 01, 2004 at 11:00:10AM -0500, Tom Lane wrote: > >> 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. > > The SQL spec thinks that a timezone is a numeric offset from UTC, full stop. > > My vision of what we will actually support is either numeric offsets or > named time zones --- basically, anything that you can now say either in > SET TIMEZONE or as a zone name in timestamptz input ought to work in > both places (as well as in AT TIME ZONE's second parameter). And a > stored timestamptz value ought to retain the full information about what > zone spec was given (for instance it should remember "PST8PDT" not just > "PST"). There was extensive discussion about this just last week. > > > 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. > > We can probably arrange to sort by UTC offset, but the sort order within > equal UTC offsets will likely be arbitrary (basically in order of the > numeric identifiers we assign to time zone names ... though that might > be user-configurable to some extent). > > > It's a backward incompatable change (or is it?) > > Some things will break, no doubt, but I don't think it will be too bad. > Certainly no worse than the changes we've made in these data types in > prior releases to move them closer to SQL spec. > > regards, tom lane > > ---------------------------(end of broadcast)--------------------------- > TIP 3: if posting/reading through Usenet, please send an appropriate > subscribe-nomail command to majordomo@postgresql.org so that your > message can get through to the mailing list cleanly > -- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (610) 359-1001 + If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square, Pennsylvania 19073
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