A method for estimating the result of a query on a database having data records arranged in tables. The database has an expected workload that includes a set of queries that can be executed on the database. An expected workload is derived including a set of queries that can be executed on the database....http://www.google.com.hk/patents/US7328221?utm_source=gb-gplus-share專利 US7328221 - Optimization based method for estimating the results of aggregate queries
