slides18 - Schedule Today: Mar. 12 (T) x Semistructured...

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Winter 2002 Arthur Keller – CS 180 18–1 Schedule Today: Mar. 12 (T) Semistructured Data, XML, XQuery. Read Sections 4.6-4.7. Assignment 8 due. Mar. 14 (TH) Data Warehouses, Data Mining. Project Part 7 due. Mar. 16 (Sa) Final Exam. 12–3PM. In class.
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Winter 2002 Arthur Keller – CS 180 18–2 Plan 1. Information integration: important new application that motivates what follows. 2. Semistructured data: a new data model designed to cope with problems of information integration. 3. XML: a new Web standard that is essentially semistructured data. 4. XQUERY: an emerging standard query language for XML data.
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Winter 2002 Arthur Keller – CS 180 18–3 Information Integration Problem: related data exists in many places. They talk about the same things, but differ in model, schema, conventions ( e.g ., terminology). Example In the real world, every bar has its own database. Some may have relations like beer-price; others have an Microsoft Word file from which the menu is printed. Some keep phones of manufacturers but not addresses. Some distinguish beers and ales; others do not.
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Winter 2002 Arthur Keller – CS 180 18–4 Two approaches 1. Warehousing : Make copies of information at each data source centrally. Reconstruct data daily/weekly/monthly, but do not try to keep it up-to-date. 2. Mediation : Create a view of all information, but do not make copies. Answer queries by sending appropriate queries to sources.
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Winter 2002 Arthur Keller – CS 180 18–5 Warehousing Wrapper Wrapper Combiner DB1 DB2 Warehouse user query result
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Winter 2002 Arthur Keller – CS 180 18–6 Mediation Wrapper Wrapper DB1 DB2 Mediator query result query result result query query result query result
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Arthur Keller – CS 180 18–7 Semistructured Data A different kind of data model, more suited to information-integration applications than either relational or OO. Think of “objects,” but with the type of an object its own business rather than the business of the class to which it belongs. Allows information from several sources, with related but different properties, to be fit together in one whole. Major application: XML documents.
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This note was uploaded on 02/21/2011 for the course CS CS 180 taught by Professor Dr.arthur during the Fall '01 term at The University of Akron.

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slides18 - Schedule Today: Mar. 12 (T) x Semistructured...

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