Functional specifications of a subsystemf or data base integrity

Abstract

This paper defines an integrity subsystem for an integrated data base management system, and shows how integrity is distinguished from the related areas of security, consistency, and reliability. The integrity subsystem guards the data base against semantic errors by per,mitting users to make assertions which define the correctness of the data base, and to specify actions.to be taken when the asserticns are not satisfied. Several categories of assertions are considered, including tuulevs. set-oriented, state- vs. transition-oriented, immediate vs. delayed, and "hard∗∗ vs. V1soft@t assertions. The related areas of data definition facilities, compatibility of data i terns, and handling of null values are explored. Facilities are specified by means of which a user may create, drop, or examine integrity assertions.