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Aggregate Functions for Approximate Query Processing
N. Jukic and S. V. Vrbsky
Department of Computer Science
The University of Alabama
Tuscaloosa, Alabama 35487-0290
Abstract
Some database systems such as medical information systems, air traffic control, and
other real-time systems, have specific time constraints for the processing of a transaction. If it is
not possible to produce an exact answer to a database query within the specified time
constraints, for many applications it may be better to produce an approximate answer than to
produce no answer at all or to wait for an exact answer and miss a deadline. Approximate query
processing can be used to provide approximate answers to database queries for such
applications. In this paper we present the theoretical basis for producing approximate answers
to aggregate functions. We extend an approximate relational algebra to include monotone
approximate aggregate functions.
keywords: approximation, approximate query processing, monotone, aggregate functions