Sql Server Analysis Services
Fast query response times and timely data refresh are two well-established performance requirements of Online Analytical Processing (OLAP) systems. To provide fast analysis, OLAP systems traditionally use hierarchies to efficiently organize and summarize data. While these hierarchies provide structure and efficiency to analysis, they tend to restrict the analytic freedom of end users who want to freely analyze and organize data on the fly.
To support a broad range of structured and flexible analysis options, Microsoft® SQL Server™ Analysis Services (SSAS) 2005 combines the benefits of traditional hierarchical analysis with the flexibility of a new generation of attribute hierarchies. Attribute hierarchies allow users to freely organize data at query time, rather than being limited to the predefined navigation paths of the OLAP architect. To support this flexibility, the Analysis Services OLAP architecture is specifically designed to accommodate both attribute and hierarchical analysis while maintaining the fast query performance of conventional OLAP databases.
Realizing the performance benefits of this combined analysis paradigm requires understanding how the OLAP architecture supports both attribute hierarchies and traditional hierarchies, how you can effectively use the architecture to satisfy your analysis requirements, and how you can maximize the architecture’s utilization of system resources.
http://msdn.microsoft.com/en-us/library/ms175609%28v=sql.90%29.aspx
