Toward a tenant-aware query rewriting engine for Universal Table schema-mapping

In software as a service (SaaS) environments, designing a multi-tenant data architecture that supports shared database with custom extension is a non-trivial task. A general approach to support such an architecture is a middleware-level facility that supports the mapping of multiple single-tenant logical schemas in the application to one multi-tenant physical schema in the database. In this paper we follow this approach and report our preliminary results on the design and analysis of a query rewriting engine that can transparently transform tenant-specific logical queries into corresponding physical queries for Universal Table, a widely adopted and industry verified schema-mapping technique. A prototype and a sample SaaS application are implemented to verify the feasibility of the design of the query rewriting engine. Besides, performance analysis results that can be used to predict the overhead of schema-mapping in the engine are also reported.