language: en

Towards an Effective Calculus for Object Query Languages

Leonidas Fegaras David Maier
Department of Computer Science and Engineering Oregon Graduate Institute of Science & Technology
20000 N.W. Walker Road P.O. Box 91000 Portland, OR 97291-1000
email: ffegaras,maierg@cse.ogi.edu

Abstract We define a standard of effectiveness for a database calculus relative to a query language. Effectiveness judges suitability to serve as a processing framework for the query language, and comprises aspects of coverage, manipulability and efficient evaluation. We present the monoid calculus, and argue its effectiveness for object-oriented query languages, exemplified 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.

1 Introduction