Is Your Cloud-Hosted Database Truly Elastic?

Elasticity has been recognized as one of the most appealing features for users of cloud services. It represents the ability to dynamically and rapidly scale up or down the allocated computing resources on demand. In practice, it is difficult to understand the elasticity requirements of a given application and workload, and to assess if the elasticity provided by a cloud service will meet these requirements. In this experience paper, we take the position that a deep understanding of the capabilities of cloud-hosted database services is a crucial requirement for cloud users in order to bring forward the vision of deploying data-intensive applications on cloud platforms. We argue that it is important that cloud users become able to paint a comprehensive picture of the relationship between the capabilities of the different type of cloud database services, the application characteristics and workloads, and the geographical distribution of the application clients and the underlying database replicas. We discuss the current elasticity capabilities of the different categories of cloud database services and identify some of the main challenges for deploying a truly elastic database tier on cloud environments. Finally, we propose a benchmarking mechanism that can evaluate the elasticity capabilities of cloud database services in different application scenarios and workloads.