A Hybrid Approach for Database Replication: Finding the Optimal Configuration between Update Everywhere and Primary Copy Paradigms

M. Liroz-Gistau, J. R. Juárez-Rodríguez, José Enrique Armendáriz-Iñigo, José Ramón González de Mendívil, Francesc D. Muñoz-Escoí

Abstract: Database replication has been subject of two different approaches, namely primary copy and update everywhere protocols. The former only allows performing update transactions in the primary replica, while the rest are only used to execute read-only transactions. Update everywhere protocols, on the other hand, allow the system to schedule update transactions in any replica, thus increasing its capacity to deal with update intensive workloads and overcoming failures. However, synchronization costs augment and its throughput may fall below the ones obtained by primary copy approaches. Under these circumstances, we propose a new database replication paradigm, halfway between primary copy and update everywhere approaches, which improve system’s performance by adapting its configuration depending on the workload submitted to the system. The core of this approach is a deterministic replication protocol which propagate changes so that broadcast transactions are never aborted. We also propose a recovery algorithm to ensure fault tolerance.