Towards practical constraint databases (extended abstract)
Stéphane Grumbach, Jianwen Su · 1996
) St ephane Grumbach I.N.R.I.A. Rocquencourt BP 105 78153 Le Chesnay, France [email protected] Jianwen Su Computer Science Department University of California Santa Barbara, California 93106, USA [email protected] Abstract We develop a framework for (real) constraint databases based on finite precision arithmetic which fulfills the main requirements of practical constraint databases. First, it allows the manipulation of approximate values, standard in scientific applications. More importantly, it permits the extension of the relational calculus with aggregate functions, while preserving the fundamental property of closed form evaluation with PTIME data complexity. This is an important step since the initial model of [KKR90] cannot be extended to aggregate functions. Moreover, finite precision computation plays a central role in efficient query processing. We introduce the finite precision semantics of queries and prove expressive power results concerning it. We then prese...