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The integration of heterogeneous data sources, which can effectively make use of the information sources and data sharing, is a hotspot within the field of current data processing research. This paper firstly describes an architecture of heterogeneous data integration system based on a Mediator-Wrapper middleware, and then makes a deep research on the XQuery query processing, especially the key issues,...
Hypothetical queries evaluate the effect of adopting or changing some strategy then aiding in decision making. Hypothetical queries simulate some modifications and assess the effect. But in OLAP environments modify data will result in cube recomputation which cost heavily. Through observing and analyzing, hypothetical queries are described as follows: first, dicing the needing hypothetical modified...
While models for data provenance have been extensively studied in the literature, the efficient evaluation of the resulting provenance queries remains an open problem. Traditional query optimization techniques, like the use of general-purpose indexes, or the materialization of provenance data, fail on different fronts to address the problem. Provenance-specific optimization techniques, like the use...
In this work we present new in-network techniques for communication efficient approximate query processing in wireless sensor nets. We use a model-based approach that constructs and maintains a spanning tree within the network, rooted at the base station. The tree maintains compressed summary information for each link that is used to ldquostub outrdquo traversal during query processing. Our work is...
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