Operations and queries in object-oriented databases supporting complex objects

Abstract In the paper, the authors attempt to extend the query model of ORION. The extension is based on adding two new features. First, is to extend relational algebra operations and set-theoretic operations to the world of classes. Second, to allow new classes to be created as a result of applying these operations on classes along the lines of relational databases. The extended query model allows a query against multiple target classes, i.e., a query that corresponds to relational join and set operations. It also enables the authors to retrieve complex objects and extracts attributes from component-type hierarchy equivalent to relational select and project operations respectively.