In postgreSQL, the default value for timestamp is "without time zone".
That's true only because the SQL standard says so, not because it's actually
a good idea to use timestamps without time zone.
Can I say when data is used among diff time zones, timestamp with time
zone is a MUST; otherwise, timestamp without time zone is used?
No. You should, IMO, use timestamp with time zone in essentially all cases.
(In particular, you should _always_ use it for recording the time at which
an event happened, which covers most uses of timestamps.) Only use timestamp
without time zone for data storage if you have a specific reason to do so.
OK. When the column is setup as "timestamp with time zone default
now()", the default values will be set based on the Operating System,
right?
An example case:
PostgreSQL server is on machine1, with timezone setup as "-5". A table
named test1(col timestamp with time zone default now() );
. insert into test1 from client machine2 with timezone "+2"; the value
inserted into machine1 should be "2006-01-04 10:01:01-05" but not
"2006-01-04 10:01:01+02" ?
. select * from test1 from client machine2, we will get "2006-01-04
10:01:01-05" since the absolute value is saved, which is never caculated
again?
. What is the problem here when the column type is setup as "timestamp
without time zone"?
The value "2006-01-04 10:01:01" is saved and read from both machine1
and machine2.
Emi
