Efficiently Supporting Adaptive Multi-Level Serializability Models in Distributed Database Systems

Informally, serializability means that transactions appear to have occurred in some total order. In this paper, we show that only the serializability guarantee with some total order is not enough for many real applications. As a complement, extra partial orders of transactions, like real-time order and program order, need to be introduced. Motivated by this observation, we present a framework that models serializable transactions by adding extra partial orders, namely multi-level serializability models. Following this framework, we propose a novel concurrency control algorithm, called bi-directionally timestamp adjustment (BDTA), to supporting multi-level serializability models in distributed database systems. We integrate the framework and BDTA into Greenplum and Deneva to show the benefits of our work. Our experiments show the performance gaps among serializability levels and confirm BDTA achieves up to 1.7× better than state-of-the-art concurrency control algorithms.