On Sep 15, 2009, at 8:50 AM, Tom Lane wrote:
See TIMEZONE_HOUR, TIMEZONE_MINUTE field specifications, in particular
b) Otherwise, let TZ be the interval value of the implicit
or explicit time zone associated with the <datetime value
expression>. If <extract field> is TIMEZONE_HOUR, then
the
result is calculated as
EXTRACT (HOUR FROM TZ)
Otherwise, the result is calculated as
EXTRACT (MINUTE FROM TZ)
I haven't tracked down whether the phrase "implicit or explicit time
zone" is hiding any interesting weasel words, but it sure *looks* like
you are supposed to be able to pull out the TZ offset
try=# select extract(timezone_hour from '2001-02-16 20:38:40 America/
Los_Angeles'::timestamptz);
date_part
-----------
0
(1 row)
That doesn't look right. AFAICT, timestamptz converts the TZ to the
default TZ and discards the specified TZ. Same with offsets:
try=# select extract(timezone_hour from '2001-02-16 20:38:40
-08:00'::timestamptz); date_part
-----------
0
(1 row)
Best,
David
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