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XML-QL: A Query Language for XML Submission to WWW Consortium August 19, 1998

XML-QL: A Query Language for XML Submission to WWW Consortium August 19, 1998. Alin Deutsch, University of Pennsylvania Mary Mernandez, AT&T Labs Daniela Florescu, INRIA Alon Levy, University of Washington Dan Suciu, AT&T Labs Reviewed by Terry E Weymouth Monday, February 14, 2000.

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XML-QL: A Query Language for XML Submission to WWW Consortium August 19, 1998

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  1. XML-QL: A Query Language for XMLSubmission to WWW Consortium August 19, 1998 Alin Deutsch, University of Pennsylvania Mary Mernandez, AT&T Labs Daniela Florescu, INRIA Alon Levy, University of Washington Dan Suciu, AT&T Labs Reviewed by Terry E Weymouth Monday, February 14, 2000

  2. Example Data <bib> <book year="1995"> <!-- A good introductory text --> <title> An Introduction to Database Systems </title> <author> <lastname> Date </lastname> </author> <publisher> <name> Addison-Wesley </name > </publisher> </book> <book year="1998"> <title> Foundation for Object/Relational Databases: The Third Manifesto </title> <author> <lastname> Date </lastname> </author> <author> <lastname> Darwen </lastname> </author> <publisher> <name> Addison-Wesley </name > </publisher> </book> </bib>

  3. Example Query WHERE <book> <title> $t </> <publisher><name>Addison-Wesley </> </> </> CONTENT_AS $p IN "www.a.b.c/bib.xml” CONSTRUCT<result><title> $t </> WHERE <author> $a</> IN $p CONSTRUCT <author> $a</> </>

  4. Results <result> <title> An Introduction to Database Systems </title> <author> <lastname> Date </lastname> </author> </result> <result> <title> Foundation for Object/Relational Databases: The Third Manifesto </title> <author> <lastname> Date </lastname> </author> <author> <lastname> Darwen </lastname> </author> </result>

  5. Some Problems Addressed • How to extract data (information?) from large XML documents or document stores. • How to exchange XML data between disparate locals (exchanging queries might be more efficient) • How to exchange XML data between different user communities • How to integrate data from multiple XML sources

  6. Components and features • Matching with Structural Patterns • Binding variables to elements in the match • construction • joining elements by value • Grouping with nested and combined queries • Binding variables to tags in the match (also Skolem functions) • Regular expressions for path matching • Construction • query results in XML • transforming XML data • Embedding queries in data

  7. Suggested Extensions • User defined predicates • Regular string expressions - element content (what about attributes) • Name Spaces • Aggregates (e.g. GROUP-BY) - with summation-type functions • Semi-joins (i.e. joins over optional elements)

  8. Comments • Data Model Features • ordered or unordered sub-elements (imposing order in results of query for unordered model!) • graph structure: semi-structured data • ID’s and ID references • Extra-structure elements • e.g. comment tags, document specifications such as occurrence and ordering information (DTD)

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