We study the properties of the magic semi-join, a new algebraic operator. In essence, a magic semi-join is the composition of a semi-join and a transitive closure. We present a theory for magic semi-joins that mirrors the theory for semi-joins; in particular, we define equivalence transformations of algebraic formulas using magic semi-joins, and we introduce the notion of full reducer program in this framework. The application of magic semi-joins is in the efficient evaluation of recursive DATALOG queries in centralized and in distributed databases.
Magic semi-joins
CERI, STEFANO;TANCA, LETIZIA;
1989-01-01
Abstract
We study the properties of the magic semi-join, a new algebraic operator. In essence, a magic semi-join is the composition of a semi-join and a transitive closure. We present a theory for magic semi-joins that mirrors the theory for semi-joins; in particular, we define equivalence transformations of algebraic formulas using magic semi-joins, and we introduce the notion of full reducer program in this framework. The application of magic semi-joins is in the efficient evaluation of recursive DATALOG queries in centralized and in distributed databases.File in questo prodotto:
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