Updating relational views using knowledge at view definition and view update time

摘要

Updating a view requires deriving a translation which converts an update on a view into updates on underlying relations. We present a pragmatic approach that uses syntactic as well as semantic knowledge to decide an appropriate translation. The semantic knowledge belongs to database and application domains and is collected at view definition time as well as at view update time. We present a rule-based approach that is applicable to simple and nested relational views defined using operations such as set difference, union, intersection, selection, projection and join operations. Our approach extends previous work by allowing more types of views, by considering more alternative translations, and most importantly, by using more types of knowledge to choose the most appropriate translation. An implementation is briefly described along with a detailed example.