Re: Timezone information

It depends on how you are declaring the timestamp field. If you do not use with time zone then the input value is open to interpretation and is not  'anchored' to a point in time.

Example

My time zone is currently PST.
test=> create table timestamp_test(id int, ts timestamp, ts_z timestamp with time zone);
CREATE TABLE
test=> insert into timestamp_test values (1, now(), now());
INSERT 0 1
.....
If you know what time zone the value was inserted under you can get it back.
.
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That assumes a lot, so the best thing is to use timestamp with time zone.