An XML-Based Approach to Publishing and Querying the History of Databases |
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Authors: | Fusheng Wang Carlo Zaniolo |
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Affiliation: | (1) Department of Computer Science, University of California, Los Angeles, CA 90095, USA |
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Abstract: | There is much current interest in publishing and viewing databases as XML documents. The general benefits of this approach
follow from the popularity of XML and the tool set available for visualizing and processing information encoded in this universal
standard. In this paper, we explore the additional and unique benefits achieved by this approach on temporal database applications.
We show that XML with XQuery can provide surprisingly effective solutions to the problem of supporting historical queries
on past content of database relations and their evolution. Indeed, using XML, the histories of database relations can be naturally
represented by temporally grouped data models. Thus, we identify mappings from relations to XML that are most conducive to
modeling and querying database histories, and show that temporal queries that would be difficult to express in SQL can be
easily expressed in standard XQuery. This approach is very general, insofar as it can be used to store the version history
of arbitrary documents and, for relational databases, it also supports queries on the evolution of their schema.
Then, we turn to the problem of supporting efficiently the storage and the querying of relational table histories. We present
an experimental study of the pros and cons of using native XML databases, versus using traditional databases, where the XML-represented
histories are supported as views on the historical tables. |
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Keywords: | relational database history temporal databases data archiving XML publishing temporal queries XQuery |
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