Patrick Valduriez

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In the context of Model Driven Engineering (MDE), models are the main development artifacts and model transformations are among the most important operations applied to models. A number of specialized languages have been proposed in order to specify model transformations. The OMG has, for instance, adopted the QVT specification. Apart from the software(More)
In new application areas of relational database systems, such as artificial intelligence, the join operator is used more extensively than in conventional applications. In this paper, we propose a simple data structure, called a join index, for improving the performance of joins in the context of complex queries. For most of the joins, updates to join(More)
Many applications in several domains such as telecommunications, network security, large-scale sensor networks, require online processing of continuous data flows. They produce very high loads that requires aggregating the processing capacity of many nodes. Current Stream Processing Engines do not scale with the input load due to single-node bottlenecks.(More)
The general problem of answering top-k queries can be modeled using lists of data items sorted by their local scores. The most efficient algorithm proposed so far for answering top-k queries over sorted lists is the Threshold Algorithm (TA). However, TA may still incur a lot of useless accesses to the lists. In this paper, we propose two new algorithms(More)
Access to large numbers of data sources introduces new problems for users of heterogeneous distributed databases. End users and application programmers must deal with unavailable data sources. Database administrators must deal with incorporating each new data source into the system. Database implementors must deal with the transformation of queries between(More)
Data-intensive Web sites serve large volumes of pages whose content is dynamically extracted from a database. Such Web sites have very high software development and maintenance costs and in general o er poor response times due to the heavy interaction with the database system. This paper introduces the Weave management system developed at INRIA, which(More)