Proxy-server architectures for OLAP

Data warehouses have been successfully employed for assisting decision making by offering a global view of the enterprise data and providing mechanisms for On-Line Analytical processing. Traditionally, data warehouses are utilized within the limits of an enterprise or organization. The growth of Internet and WWW however, has created new opportunities for data sharing among ad-hoc, geographically spanned and possibly mobile users. Since it is impractical for each enterprise to set up a worldwide infrastructure, currently such applications are handled by the central warehouse. This often yields poor performance, due to overloading of the central server and low transfer rate of the network. In this paper we propose an architecture for OLAP cache servers (OCS). An OCS is the equivalent of a proxy-server for web documents, but it is designed to accommodate data from warehouses and support OLAP operations. We allow numerous OCSs to be connected via an arbitrary network, and present a centralized, a semi-centra lized and an autonomous control policy. We experimentally evaluate these policies and compare the performance gain against the existing systems where caching is performed only at the client side. Our architecture offers increased autonomy at remote clients, substantial network traffic savings, better scalability, lower response time and is complementary both to existing OLAP cache systems and distributed OLAP approaches.