Nikolay Samokhvalov <samokhvalov(at)gmail(dot)com> writes:
> Forget about SERIAL. I have INTEGER column with some expression as
> DEFAULT in it.
No, you have a SERIAL column that you've improperly mucked with the
implementation of. If you'd declared it as INTEGER to start with,
you could do whatever you wanted to its default expression.
regards, tom lane