Multisystem Coupling by a Combination of Data Sharing and Data Partitioning

Abstract

In a multisystem partitioned database system, the databases are partitioned among the multiple systems and a facility is provided to support the shipping of database requests among the systems. In contrast, in the data sharing multisystem approach, all systems have direct access to the shared database. There are a number of tradeoffs between these two approaches. In this paper we propose and evaluate a hybrid architecture that combines the approaches, and offers the advantages of each. Some databases are shared between systems, while others are retained private by specific systems. The issue is to determine which databases to share, which to retain private, and how to route transactions and partition the private databases among systems so as to minimize response time or overheads, while balancing the load among systems. A simulated annealing heuristic is used to solve this optimization problem. Trace data from large mainframe systems running IBM's IMS database management system are used to illustrate the methodology and to demonstrate the advantages of the hybrid approach. © 1989 IEEE