A General Procedure to Test Containment of Conjunctive Queries.
Miguel R. Penabad, Nieves R. Brisaboa, José Ramón Paramá, Hendrik Decker · 2001
Equivalence and containment of queries is a crucial issue of database query optimization theory. Among the dierent perspectives used to study this problem, we consider in this work two orthogonal ones: the presence of inequalities in the queries, and the underlying semantics, that can be set or bag theoretic. This work presents a general algorithmic skeleton, QCC (Query containment Checker), that can be used to check the containment of queries with or without inequalities, under set or bag semantics. 1