Aggregation tables are tables that contain summaries of fact table information. These tables are used to improve query performance when SQL is used as the query mechanism. OLAP technology, such as that provided by Microsoft® SQL Server™ 2000 Analysis Services, eliminates the need for such tables. Analysis Services creates OLAP cubes that contain preaggregated summaries so that queries can be answered quickly, regardless of the level of summarization required to answer the query. It is not necessary to create aggregation tables in the data warehouse when Analysis Services is used to provide presentation services. Analysis Services creates aggregations as necessary and stores them in tables in the data warehouse database or in internal multidimensional structures. For more information, see Analysis Services Overview.