Extending Mixed Serialisation Graphs to Replicated Environments

Replication has been told to be a solution to provide scalability and high availability in databases. Unfortunately, the cost of ensuring isolated and consistent executions is sometimes too high. Weakest isolation models have proved to be a way to reduce this cost but they can violate some applications transactions isolation needs. In stand-alone systems, models supporting different isolation restrictions for concurrent transaction are used to avoid this dilemma. With this kind of protocols, applications can specify every transaction isolation requirements. However, how to extend these models to replicated systems is still an issue. In this paper we extend Adya´s model based on serialization graphs as a first step to construct replication protocols with such a feature.