Re: to_timestamp() and timestamp without time zone

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