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Technical Report Details


Date 25-3-2003
Number DISI-TR-03-05
Title Equivalence Preserving transformation for XML Documents
Authors Stephan Bressan, Barbara Catania, Zoe Lacroix, Ying G. Li, Anna Maddalena.
Bibtex Entry
E-mail catania@disi.unige.it
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Abstract Efficient XML document management requires the usage of specific storage and indexing approaches. However, some organizations may not want to disrupt their information management strategy and may not need or wish to store and manage native XML data but rather only process transient XML data received from other organizations. These organizations may benefit of the usage of query processors that are only loosely-coupled with the storage system. Such query processors operate on an internal representation of XML documents and thus leverage neither the XML storage structure nor the possible access methods dedicated to this storage structure supported by dedicated XML management systems. Different solutions have therefore to be proposed for query optimization in these environments. In this paper, we present a query optimization approach for loosely-coupled environments based on two main steps: first, based on the query, input documents are transformed on the fly, at query execution time, by pruning parts that are irrelevant with respect to the query; then the query is executed on the resulting pruned documents. An index structure is also provided to further optimize the pruning process. Experimental results show that, by using the proposed pruning strategy, query execution time can be significantly reduced.
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