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C. Cumbo, W. Faber, G. Greco:
"Improving Query Optimization for Disjunctive Datalog";
Vortrag: APPIA-GULP-PRODE 2003 - 2003 Joint Conference on Declarative Programming, Reggio Calabria, Italy; 03.09.2003 - 05.09.2003; in: "APPIA-GULP-PRODE 2003 - 2003 Joint Conference on Declarative Programming", F. Buccafurri (Hrg.); (2003), S. 252 - 262.

In this paper we present a technique for the optimization of
(partially) bound queries over disjunctive deductive databases. In
particular, we extend the magic-set optimization technique
(originally defined for non-disjunctive deductive databases) to
the disjunctive case. The method presented in this paper improves
a similar approach presented in [7] by reducing the
number of additionally introduced predicates and rules.

One drawback, which is intrinsic to both techniques, is that
redundant rules may be created frequently. In order to overcome
this, we present a method for identifying such superfluous rules,
which may subsequently be deleted without changing the semantics,
thereby reducing the size of the rule-base, an important
performance factor.

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