The leganet system: Freshness-aware transaction routing in a database cluster

We consider the use of a database cluster for Application Service Provider (ASP). In the ASP context, applications and databases can be update-intensive and must remain autonomous. In this paper, we describe the Leganet system which performs freshness-aware transaction routing in a database cluster. We use multi-master replication and relaxed replica freshness to increase load balancing. Our transaction routing takes into account freshness requirements of queries at the relation level and uses a cost function that takes into account the cluster load and the cost to refresh replicas to the required level. We implemented the Leganet prototype on an 11-node Linux cluster running Oracle8i. Using experimentation and emulation up to 128 nodes, our validation based on the TPC-C benchmark demonstrates the performance benefits of our approach.