176 search results - page 3 / 36 » Answering aggregate queries in data exchange |
ICDT
2009
ACM
14 years 6 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...
PODS
2005
ACM
14 years 5 months ago
2005
ACM
Abstract. We present a semantics and answer set programs for relational peer data exchange systems. When a peer answers a query, it exchanges data with other peers in order to supp...
ICDE
2012
IEEE
11 years 8 months ago
2012
IEEE
— Uncertainties in data arise for a number of reasons: when the data set is incomplete, contains conflicting information or has been deliberately perturbed or coarsened to remov...
TKDE
2012
11 years 8 months ago
2012
—Continuous queries are used to monitor changes to time varying data and to provide results useful for online decision making. Typically a user desires to obtain the value of som...
AMW
2009
13 years 6 months ago
2009
We investigate the space requirements for summaries needed for maintaining exact answers to aggregate queries over histories of relational databases. We show that, in general, a su...