On Extending the Primary-copy Database Replication Paradigm

In database replication, primary-copy systems sort out easily the problem of keeping replicate data consistent by allowing only updates at the primary copy. While this kind of systems are very efficient with workloads dominated by read-only transactions, the update-everywhere approach is more suitable for heavy update loads. However, it behaves worse when dealing with workloads dominated by read-only transactions. We propose a new database replication paradigm, halfway between primary-copy and update-everywhere approaches, which permits improving system performance by adapting its configuration to the workload, by means of a deterministic database replication protocol which ensures that broadcast writesets are always going to be committed.