Centralized Versus Distributed Index Management in a Page Server OODBMS

Abstract

Recent work on client-server data-shipping OODBs has demonstrated the usefulness of local data caching at client sites. However, none of the studies has investigated index-related performance issues in particular. References to index pages arise from associative queries and from updates on indexed attributes, often making indexes the most heavily used hot spots in a database. System performance is therefore quite sensitive to the index management scheme. This paper examines the effects of index caching, and investigates two schemes, one centralized and the other distributed, for index page management. In the centralized scheme, index pages are not allowed to be cached at client sites; thus, communication with the central server is required for all index-based queries and index updates. The distributed index management scheme supports inter-transaction caching of index pages at client sites, and enforces a distributed index consistency control protocol similar to that of data pages. We study via simulation the behavior of these two index management schemes under several different workloads and contention profiles, and identify scenarios where each of the two schemes performs better than the other. For more information please write to ark@cs.stanford.edu. 1