Object Views and Database Restructuring

摘要: We present a formal data model for views in Object DataBase Systems (ODBS) as transformation mechanism databases. Our relaxes the usual coustraiul, where an object belongs to single class while using generalization of referent and eatables deterministic creation derived objects with complex identifiers. define IQL-like language which enables manipulation such referents. The view-based is achieved two steps: extension source instance followed by projection extended instance. can be carried ont four algebraic operators, namely projection, join-specialization, join generalization, that specify both virtual sclaetna its corresponding This simple algebra call express most view operators proposed literature ad provides real restructuring schema