Most data warehouse practitioners create aggregated data tables to improve the performance of highly summarized queries. The aggregate tables store precomputed results that are combined measures, usually summed, over a set of dimensional attributes. Use aggregate tables to improve query response times in decision support systems.
If you write SQL queries or use a tool that only understands what physical tables exist and not their meaning, then using aggregate tables becomes more complex as the number of aggregate tables increases. The Oracle BI Server’s aggregate navigation capability enabled queries to use the information stored in aggregate tables automatically. The Oracle BI Server lets you concentrate on asking the right business question, and then the server decides which tables provide the fastest answers.
Oracle Business Intelligence takes advantage of the aggregates in source databases. See Managing Logical Table Sources (Mappings). The Oracle Business Intelligence aggregate persistence automates the creation and loading of the aggregate tables and their corresponding Oracle Business Intelligence metadata mappings to minimize the time required to create and maintain the data aggregation, as well as load database scripts and the corresponding metadata mappings.
This chapter contains the following topics: