Centralized versus Distributed Index Schemes in OODBMS-A Performance Analysis

Recent work on client-server data-shipping OODBs has demonstrated the usefulness of local data caching at client sites. In addition to data caching, index caching can provide substantial benefits through associative access to cached objects. Indexes usually have high contention, and database performance is quite sensitive to the index management scheme. This paper examines the effects of two index caching schemes, one centralized and the other distributed, for index page management in a page server OODB. In the centralized scheme, index pages are not allowed to be cached at client sites and are managed by the server. 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 performance 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.