Denis Zaitsev <zzz@anda.ru> writes:
> create table xxx (
> s text,
> t timestamp
> default 'now'
> );
That's a dangerous way to define the default --- 'now' is taken as a
literal of type timestamp, which means it will be reduced to a timestamp
constant as soon as a statement that requires the default is planned.
You lose in plpgsql because of plan caching, but you'd also lose if you
tried to PREPARE the insert command. Example:
regression=# insert into xxx values('a');
INSERT 154541 1
regression=# insert into xxx values('b');
INSERT 154542 1
regression=# prepare s(text) as insert into xxx values($1);
PREPARE
regression=# execute s('q1');
EXECUTE
regression=# execute s('q2');
EXECUTE
regression=# select * from xxx;s | t
----+----------------------------a | 2003-07-26 10:18:51.364913b | 2003-07-26 10:18:53.519648q1 | 2003-07-26
10:19:21.795415q2| 2003-07-26 10:19:21.795415
(4 rows)
The default would work the way you want with almost any other way of
doing it. For instance
default now()default current_timestampdefault localtimestampdefault 'now'::text
Given that you want timestamp without time zone, I'd probably use
"default localtimestamp".
regards, tom lane