From: | Adrian Klaver <adrian(dot)klaver(at)gmail(dot)com> |
---|---|
To: | pgsql-general(at)postgresql(dot)org |
Cc: | hernan gonzalez <hgonzalez(at)gmail(dot)com> |
Subject: | Re: to_timestamp() and timestamp without time zone |
Date: | 2011-06-26 20:13:36 |
Message-ID: | 201106261313.37075.adrian.klaver@gmail.com |
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Lists: | pgsql-general |
On Sunday, June 26, 2011 12:57:15 pm hernan gonzalez wrote:
>
> An instant is a point in the universal time, it's a physical concept,
> unrelated to world calendars. The time point at which the man first landed
> on the moon is an instant, as is the moment at which my server restarted.
> It is not related to a Timezone at all. We can specified it by some
> arbitrary convention (milliseconds passed since the first atomic explosion
> at Hiroshima), or by some human calendar at some place/moment: for
> example, the "wall date and clock used at New York". If (only if) you use
> a Gregorian Calendar to specify/show a instant, you need a date, a time
> and a timezone. (but you have many timezones to choose from - as you have
> several calendars - a timezone is not determined by an instant). A full
> datetime (date, time, timezone) implies an instant - but an instant does
> not imply a timezone.
You might want to review the Theories of Relativity, which pretty much blew away
the notion of an absolute time and introduced the notion of frame of reference
for time.
--
Adrian Klaver
adrian(dot)klaver(at)gmail(dot)com
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