59 search results - page 6 / 12 » Rewriting Unions of General Conjunctive Queries Using Views |
PODS
2012
ACM
11 years 10 months ago
2012
ACM
Data is increasingly being bought and sold online, and Webbased marketplace services have emerged to facilitate these activities. However, current mechanisms for pricing data are ...
DBSEC
2006
13 years 8 months ago
2006
Most state-of-the-art approaches of securing XML documents are based on a partial annotation of an XML tree with security labels which are later propagated to unlabeled nodes of th...
EDBT
2012
ACM
11 years 9 months ago
2012
ACM
In this paper we consider the problem of answering queries using views, with or without ontological constraints, which is important for data integration, query optimization, and d...
ICDT
2012
ACM
11 years 10 months ago
2012
ACM
We introduce a representation system for relational data based on algebraic factorisation using distributivity of product over union and commutativity of product and union. We giv...
PODS
2010
ACM
14 years 16 days ago
2010
ACM
Both semantic and type-based query optimization rely on the idea that queries often exhibit non-trivial rewritings if the state space of the database is restricted. Despite their ...