Expressing and Processing Path-centric XML Queries
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Date
2012-04-02T09:09:42Z
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Abstract
The support for navigation and browsing in XML query languages is based on XPath. XQuery, a W3C standardized XML query language, introduces FLOWR constructs on top of XPath, to express more complex query purposes. However, a family of very practical queries, which aim to return or manipulate paths as first class objects, cannot be expressed by XPath or XQuery FLOWR expressions.
We call them path-centric queries. Of course, a user can program an XQuery user-defined recursive function to meet pathcentric queries, but the concern is the convenience and practicality
of requiring normal database users to be equipped with programming skills. In this paper, we analyze the root cause of the limited expressivity of XPath and XQuery for path-centric queries.
Based on the analysis, we propose seamless extension to XQuery FLOWR to elegantly express path-centric queries. We further investigate
intra-path aggregation, an analytical operation in pathcentric queries, and show how they can be easily expressed and efficiently processed.