Practical Predicate Placement

Abstract

Recent work in query optimization has addressed the issue of placing expensive predicates in a query plan. In this paper we explore the predicate placement options considered in the Montage DBMS, presenting a family of algorithms that form successively more complex and effective optimization solutions. Through analysis and performance measurements of Montage SQL queries, we classify queries and highlight the simplest solution that will optimize each class correctly. We demonstrate limitations of previously published algorithms, and discuss the challenges and feasibility of implementing the various algorithms in a commercial-grade system. © 1994, ACM. All rights reserved.