Combining Indexing Technique with Path Dictionaryfor Nested Object

107 Combining Indexing Technique with Path Dictionary for Nested Object Queries Wang-Chien Lee Dept. of Computer & Information Science The Ohio State University Columbus, Ohio 43210-1277, USA [email protected], FAX: 614-292-2911 Dik Lun Lee* Department of Computer Science Hong Kong University of Science & Technology Clear Water Bay, Hong Kong [email protected], FAX: 852-358-1477 Abstract A path dictionary encodes the connections among objects in the aggregation hierarchy. It has been shown to be an e cient mechanism for supporting nested object queries [6]. In this paper, we present a new method, called the path dictionary index method, which combines indexing techniques with the path dictionary method. We describe the operations of the new mechanism and develop cost models for its storage overhead and query and update costs. Finally, we compare the new mechanism to the path index method [3]. The result shows that the path dictionary index method is signi cantly better than the path index method over a wide range of parameters.