Placement of partitioned signature file and its performance analysis

Abstract

Signature file access method is widely used in information retrieval and database. It acts as a search filter for content-based retrieval. One of the efficient organizations of signature file is Quick Filter. Quick Filter partitions the signatures into signature pages using linear hashing. While seek and latency time dominate the performance of disk access, efficient placement of the partitioned signature pages is necessary. In this paper, we investigate the placement of partitioned signature file to minimize the number of clusters pertinent to the query signature in dynamic environment. We present the placement using Gray code to minimize the number of qualified clusters. To accommodate the dynamic feature, linear hashing for partitioning the signatures into Gray code order is modified. The performance measured by the number of clusters accessed is analyzed. The formula of performance for a specific query signature is also derived. It is useful for the access cost estimation of query optimization in information retrieval. Performance analysis shows that placement using Gray code order outperforms that using binary code code. (C) Elsevier Science Inc. 1998.