An algebraic approach to the manipulation of complex objects

The authors present an algebra (LOA) for complex objects, which has been developed within LOGIDATA+, a national project funded by the Italian National Research Council, as an internal language in a prototype system for the management of extended relational databases with complex object types. The object algebra is a set-oriented manipulation language that plays in the object oriented DBMS the same role as the relational algebra in a relational system. That is providing efficient access to mass storage structures and simplifying query optimization. The algebra refers to a data model that includes structured data types and object identity, thus allowing both classes of objects and value-based relations. The algebra has required extension of the semantics of operators with respect to the nested relation model, and to introduce additional operators for type conversion and OID invention. The paper also briefly discusses the implementation of the primitives of the object algebra in the prototype by means of the operators of the relational algebra