Querying combined cloud-based and relational databases.

An increasing amount of data is stored in cloud repositories, which provide high availability, accessibility, and scalability. However, for security reasons enterprises often need to store the core proprietary data in their own relational databases, while common data to be widely available can be stored in a cloud data repository. For example, the subsidiaries of a global enterprise are located in different geographic places where each subsidiary is likely to maintain its own local database. In such a scenario, data integration among the local databases and the cloud-based data is inevitable. We have developed a system called BigIntegrator to enable general queries that combine data in cloud-based data stores with relational databases. We present the design and working principle of the system. A scenario of querying data from both kinds of data sources is used as illustration. The system is general and extensible to integrate data from different kinds of data sources. A particular challenge being addressed is the limited query capabilities of cloud data stores. BigIntegrator utilizes knowledge of those limitations to produce efficient query execution.