timestamp error cant find class for type 1296

When attempting to create the following table:

CREATE TABLE test (
                                id timestamp primary key,
                                fodder varchar(64)
                                );


I get the following error:
ERROR:  Can't fine a default operator CLASS for type 1296

Whats that all about? ;)

If I create the table as follows (which AFAIK is equivilant):
CREATE TABLE test2 (
                                id datetime primary key,
                                fodder varchar(64)
                                );

It creates fine but when I try to insert something like:

INSERT INTO test2 (fodder) VALUES ('arfarf');

I get:
ERROR: ExecAppend: Fail to add null value in not null value attribute id

I thought that the datetime field would be filled automatically on a insert with a current timestamp. can someone point
outwhat Im doin wrong. 

Thnx all,
-crypt0genic



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