On multisystem coupling through function request shipping

In a multisystem database system with a function request shipping approach, the databases are partitioned among the multiple systems and a facility is provided to support the shipping of database requests among the systems. This is in contrast to a data sharing multisystem approach in which all systems have direct access to the shared database. The performance of the two approaches is compared, emphasizing generic issues that affect the function shipping approach. A methodology is presented for partitioning the databases and routing transactions among the systems so as to minimize the fraction of remote function calls, while balancing the load among systems. Estimates of the resulting remote function calls, mirror transaction setups, and multisystem two-phase commits are obtained. Results of simulation and approximate analysis are presented.