19 search results - page 3 / 4 » An optimization of disjunctive queries: union-pushdown |
ICDT
2005
ACM
14 years 4 months ago
2005
ACM
We study the problem of rewriting queries using views in the presence of access patterns, integrity constraints, disjunction, and negation. We provide asymptotically optimal algori...
ICDT
2009
ACM
14 years 11 months ago
2009
ACM
The class of unions of conjunctive queries (UCQ) has been shown to be particularly well-behaved for data exchange; its certain answers can be computed in polynomial time (in terms...
SCCC
2005
IEEE
14 years 4 months ago
2005
IEEE
Databases may not satisfy integrity constraints (ICs) for several reasons. Nevertheless, in most of the cases an important part of the data is still consistent wrt certain desired...
DBPL
2001
Springer
14 years 3 months ago
2001
Springer
Abstract. We are interested in the theoretical foundations of the optimization of conjunctive regular path queries (CRPQs). The basic problem here is deciding query containment bot...
DLOG
2007
14 years 1 months ago
2007
We present cq-programs, which enhance nonmonotonic description logics (dl-) programs by conjunctive queries (CQ) and union of conjunctive queries (UCQ) over Description Logics kno...