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Aggregate Functions for Approximate Query Processing

N. Jukic and S. V. Vrbsky

[email protected]

[email protected]

Department of Computer Science

The University of Alabama

Tuscaloosa, Alabama 35487-0290


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