Abstract

The goal of this work is to integrate in a general framework the different query optimization techniques that have been proposed in the object-oriented context. As a first step, we focus essentially on the logical aspect of query optimization. In this paper, we propose a formalism (i) that unifies different rewriting formalisms, (ii) that allows easy and exhaustive factorization of duplicated subqueries, and (iii) that supports heuristics in order to reduce the optimization rewriting phase. 1 Introduction Many declarative query languages for object-oriented database management systems have been proposed in the last few years (e.g. [4, 5, 9]). Currently, a very serious concern is their optimization. Interesting techniques have been imported from other environments or developed for this context. However, although complementary, these techniques are often supported by distinct formalisms. The implementation of a query optimizer is thus still an awkward and delicate operation. Clearly, i...

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