Containment of aggregate queries
MetadataShow full item record
SubjectDatabase management; Computation by abstract devices; Mathematical logic and formal languages; Information storage and retrieval; Information systems applications; Business information systems
The problem of deciding containment of aggregate queries is investigated. Containment is reduced to equivalence for queries with expandable aggregation functions. Many common aggregation functions, such as max, cntd (count distinct), count, sum, avg, median and stdev (standard deviation) are shown to be expandable. It is shown that even in the presence of integrity constraints, containment can be reduced to equivalence. For conjunctive count and sum-queries, simpler characterizations for containment are given, that do not require checking equivalence. These results are built upon in order to solve the problem of finding maximally-contained sets of rewritings for conjunctive count-queries
Showing items related by title, author, creator and subject.
Jannach D; Zanker M; Ge M; Gröning M (Springer Berlin Heidelberg, 2012)The paper reviews and classifies recent research in recommender systems both in the field of Computer Science and Information Systems. The goal of this work is to identify existing trends, open issues and possible directions ...
Byrom, R; Coghlan, B; Cooke, A; Cordenonsi, R; Cornwall, L; Craig, M; Djaoui, A; Duncan, A; Fisher, S; Gray, A; Hicks, S; Kenny, S; Leake, J; Lyttleton, O; Magowan, J; Middleton, R; Nutt, W; O'Callaghan, D; Podhorszki, N; Taylor, P; Walk, J; Wilson, A (Springer, 2005)R-GMA (Relational Grid Monitoring Architecture)  is a grid monitoring and information system that provides a global view of data distributed across a grid system. R-GMA creates the impression of a single centralised ...