Supporting Database Applications as a Service

Multi-tenant data management is a form of software as a service (SaaS), whereby a third party service provider hosts databases as a service and provides its customers with seamless mechanisms to create, store and access their databases at the host site. One of the main problems in such a system, as we shall discuss in this paper, is scalability, namely the ability to serve an increasing number of tenants without too much query performance degradation. A promising way to handle the scalability issue is to consolidate tuples from different tenants into the same shared tables. However, this approach introduces two problems: 1) The shared tables are too sparse. 2)Indexing on shared tables is not effective. To resolve the problems, we propose a multi-tenant database system called M-Store, which provides storage and indexing services for multi-tenants. To improve the scalability of the system, we develop two techniques in M-Store: bitmap interpreted tuple (BIT) and multi-separated index (MSI). BIT is efficient in that it does not store NULLs from unused attributes in the shared tables and MSI provides flexibility since it only indexes each tenant´s own data on frequently accessed attributes. We extended MySQL based on our proposed design and conducted extensive experiments. The experimental results show that our proposed approach is a promising multi-tenancy storage and indexing scheme which can be easily integrated into existing DBMS.