Load sharing in hybrid distributed-centralized database systems

In a hybrid distributed-centralized database system architecture, some transactions run at (geographically) distributed systems, and other transactions at a central computing complex. Static and dynamic load-sharing strategies are studied for such systems. The strategies take into account not only the difference in load at different sites, but also the effect of routing on data-contention and transaction-abort probabilities. Five dynamic strategies are examined and are compared with an optimal static strategy. A dynamic strategy that is based on analytical estimates of the effect of routing on all transactions in the system, rather than that on the incoming transaction alone, is found to be the best