language: en

OBJECT-ORIENTED QUERIES: EQUIVALENCE AND OPTIMIZATION

Gail M. Shaw and Stanley B. Zdonik
Department of Computer Science Brown University
Providence, R.I. 02912

We are interested in efficiently accessing data in an object-oriented database. We have developed a query algebra which fully supports object identity and abstract data types, and have identified a variety of algebraic query transformations. The equivalence of two queries is complicated by the presence of object identity. In this paper we define a hierarchy of notions of equivalence for queries, and present examples of equivalent query transformations for each level of the hierarchy.

1. INTRODUCTION