Re: Why extract( ... from timestamp ) is not immutable?

On Wed, Jan 25, 2012 at 07:37:44AM -0800, Adrian Klaver wrote:
> Its not the extract part but the at time zone part see:
>
> http://www.postgresql.org/docs/9.0/interactive/functions-datetime.html#FUNCTIONS-DATETIME-ZONECONVERT

not sure what you mean - timestamptz at time zone converts to timestamp
(without time zone), and it shows predictable results:
$ begin;
BEGIN

*$ set timezone = 'EST';
SET

*$ select now() at time zone 'UTC';
          timezone
────────────────────────────
 2012-01-25 15:43:31.048171
(1 row)

*$ set timezone = 'CET';
SET

*$ select now() at time zone 'UTC';
          timezone
────────────────────────────
 2012-01-25 15:43:31.048171
(1 row)

both timestamps returned are the same.

Best regards,

depesz

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