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Wavelet synopses for general error metrics
Minos Garofalakis, Amit Kumar
Several studies have demonstrated the effectiveness of the wavelet decomposition as a tool for reducing large amounts of data down to compact wavelet synopses that can be used to obtain fast, accurate approximate query answers. Conventional...
XPath 1.0 is a variable free language designed to specify paths between nodes in XML documents. Such paths can alternatively be specified in first-order logic. The logical abstraction of XPath 1.0, usually called Navigational or Core XPath, is not...
Graph indexing based on discriminative frequent structure analysis
Xifeng Yan, Philip S. Yu, Jiawei Han
Graphs have become increasingly important in modelling complicated structures and schemaless data such as chemical compounds, proteins, and XML documents. Given a graph query, it is desirable to retrieve graphs quickly from a large database...
Composing schema mappings: Second-order dependencies to the rescue
Ronald Fagin, Phokion G. Kolaitis, Lucian Popa, Wang-Chiew Tan
A schema mapping is a specification that describes how data structured under one schema (the source schema) is to be transformed into data structured under a different schema (the target schema). A fundamental problem is composing schema mappings:...
Optimization of query streams using semantic prefetching
Ivan T. Bowman, Kenneth Salem
Streams of relational queries submitted by client applications to database servers contain patterns that can be used to predict future requests. We present the Scalpel system, which detects these patterns and optimizes request streams using...
Synopses for query optimization: A space-complexity perspective
Raghav Kaushik, Jeffrey F. Naughton, Raghu Ramakrishnan, Venkatesan T. Chakravarthy
Database systems use precomputed synopses of data to estimate the cost of alternative plans during query optimization. A number of alternative synopsis structures have been proposed, but histograms are by far the most commonly used. While histograms...