A hybrid distributed centralized system structure for transaction processing

A hybrid system structure comprised of distributed systems to take advantage of locality of reference and a central system to handle transactions that access non-local data is examined. Several transaction processing applications, such as reservation systems, insurance and banking have such regional locality of reference. A concurrency and coherency control protocol that maintains the integrity of the data and performs well for transactions that access local or non-local data is described. It is shown that the performance of the hybrid system is much less sensitive to the fraction of remote accesses than the distributed system and offers similar performance to the distributed system for local transactions