A method for generating an approximate answer to a query in a database environment in which the database has a plurality of base relations. A query relating to a database is received, and an approximate answer to the query is generated such that the approximate answer is based on at least one join synopsis...http://www.google.com.au/patents/US6477534?utm_source=gb-gplus-sharePatent US6477534 - Method and system for generating a statistical summary of a database using a join synopsis
