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The problem of answering queries using views is to find efficient methods of answering a query using a set of previously materialized views over the database, rather than accessing the database relations. The problem has received significant attention because of its relevance to a wide variety of data management problems, such as data integration, query(More)
Many problems encountered when building applications of database systems involve the manipulation of models. By "model," we mean a complex structure that represents a design artifact, such as a relational schema, object-oriented interface, UML model, XML DTD, web-site schema, semantic network, complex document, or software configuration. Many uses of models(More)
We present HePToX, a full-fledged peer-to-peer database system that efficiently handles XML data heterogeneity. In a highly dynamic P2P network, it is unrealistic for a peer entering the network to be forced to agree on a global mediated schema, or to perform heavyweight operations for mapping its schema to neighboring schemas. In our demo, we show that to(More)
Researchers in the life-sciences are currently limited to small-scale informatics experiments and analyses because of the lack of interoperability among life-sciences web services. This limitation can be addressed by annotating services and their interfaces with semantic information, so that interoperability problems can be reasoned about programmatically.(More)
We address the problem of generating a mediated schema from a set of relational data source schemas and conjunctive queries that specify where those schemas overlap. Unlike past approaches that generate only the mediated schema, our algorithm also generates view definitions, i.e., source-to-mediated schema mappings. Our main goal is to understand the(More)
Data warehouses are overwhelmingly built through a bottom-up process , which starts with the identification of sources, continues with the extraction and transformation of data from these sources, and then loads the data into a set of data marts according to desired multidimensional relational schemas. End user business intelligence tools are added on top(More)