TY - GEN
T1 - Constraints and redundancy in Datalog
AU - Levy, Alon
AU - Sagiv, Yehoshua
PY - 1992
Y1 - 1992
N2 - Two types of redundancies in datalog programs are considered. Redundancy based on reachability eliminates rules and predicates that do not participate in any derivation tree of a fact for the query predicate. Redundancy based on irrelevance is similar, but considers only minimal derivation trees, that is, derivation trees having no pair of identical atoms, such that one is an ancestor of the other. Algorithms for detecting these redundancies are given, including the case of programs with constraint literals. These algorithms not only detect redundancies in the presence of constraints, but also push constraints from the given query and rules to the EDB predicates. Under certain assumptions discussed in the paper, the constraints are pushed to the EDB as tightly as possible.
AB - Two types of redundancies in datalog programs are considered. Redundancy based on reachability eliminates rules and predicates that do not participate in any derivation tree of a fact for the query predicate. Redundancy based on irrelevance is similar, but considers only minimal derivation trees, that is, derivation trees having no pair of identical atoms, such that one is an ancestor of the other. Algorithms for detecting these redundancies are given, including the case of programs with constraint literals. These algorithms not only detect redundancies in the presence of constraints, but also push constraints from the given query and rules to the EDB predicates. Under certain assumptions discussed in the paper, the constraints are pushed to the EDB as tightly as possible.
UR - http://www.scopus.com/inward/record.url?scp=0026990406&partnerID=8YFLogxK
U2 - 10.1145/137097.137111
DO - 10.1145/137097.137111
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AN - SCOPUS:0026990406
SN - 0897915194
SN - 9780897915199
T3 - Proceedings of the ACM SIGACT-SIGMOD-SIGART Symposium on Principles of Database Systems
SP - 67
EP - 80
BT - Proceedings of the ACM SIGACT-SIGMOD-SIGART Symposium on Principles of Database Systems
PB - Publ by ACM
T2 - Proceedings of the 11th ACM SIGACT-SIGMOD-SIGART Symposium on Principles of Database Systems
Y2 - 2 June 1992 through 4 June 1992
ER -