Towards an E ective Calculus for Object Query Languages

We deene a standard of eeectiveness for a database calculus relative to a query language. EEectiveness judges suitability to serve as a processing framework for the query language, and comprises aspects of coverage, manipulability and eecient evaluation. We present the monoid calculus, and argue its eeectiveness for object-oriented query languages, exempliied by OQL of ODMG-93. The monoid calculus readily captures such features as multiple collection types, aggregations, arbitrary composition of type constructors and nested query expressions. We also show how to extend the monoid calculus to deal with vectors and arrays in more expressive ways than current query languages do, and illustrate how it can handle identity and updates.