Query optimization using rewrite rules

Abstract

In this paper we present a normal form for a relational algebra, consisting of Projection, Selection and Join, extended with Calculation and Union and define a corresponding language UPCSJL. The construction of this normal form, using unconditional rewrite rules, already provides some optimization. Further optimization can be achieved efficiently by applying conditional rewrite rules that directly operate on the normal form. This approach is compared to more traditional query optimization techniques that do not apply normalization.