Under certain circumstances (cant remember when it does not work, play around with col-type serial vs integer ) something like this in the class definition will work

(id :initarg :id :initform nil
       :col-type serial :col-default (:nextval "reporting-period-id-seq"))

or

when you initialize a new dao-class  use something like this

:id (query (:select (:nextval "reporting-period-id-seq")) :single)