PRIMARY KEY constraint questions.

Hi ,

I try to move my old SQLAnywhere database to PostgreSQL 7.1 and found
some problem.

I can't perform next DDL:

ALTER TABLE xxx ADD PRIMARY KEY ( a, b );

And some questions:
1. Does anybody know what type of indext create PRIMARY KEY constraint
and how I can change this type?
2. How I can create primary key constraint without index?

Thanks.
--
Best regards,
 Viacheslav                          mailto:taras@deka.kp.km.ua