Histogram-based approximation of set-valued query-answers

摘要

A method for generating an approximate answer in response to a query to a database in which an SQL query Q for operating on a relation R in a database is received. Relation R has an associated histogram H. The SQL query Q is translated to be a query Q' for operating on histogram H. Translated query Q' is executed on histogram H for obtaining a result histogram. The result histogram is expanded into a relation having tuples containing approximate attribute values.