On transaction liveness in replicated databases

This paper makes a first attempt to give a precise characterisation of liveness in replicated database systems. We introduce the notion of liveness degrees, which express the expectation a database user might have about the termination of its transactions, despite concurrency and failures. Our liveness degrees are complementary to the traditional transactional safety degrees (e.g., serializability) and lead to a better characterisation of the reliability of database replication protocols. We present a generic framework that abstracts several well-known replication protocols and we point out an interesting trade-off between live-ness and safety properties in these protocols