Answering queries using views /
By: Afrati, Foto [author.].
Contributor(s): Chirkova, Rada [author.].
Material type:
BookSeries: Synthesis digital library of engineering and computer science: ; Synthesis lectures on data management: #54.Publisher: [San Rafael, California] : Morgan & Claypool, [2019]Edition: Second edition.Description: 1 PDF (xix, 253 pages) : illustrations.Content type: text Media type: electronic Carrier type: online resourceISBN: 9781681734637.Subject(s): Querying (Computer science) | conjunctive queries | aggregate queries | arithmetic comparisons | negation | acyclic queries | query containment | query equivalence | equivalent query rewritings | maximally contained query rewritings | tuple-generating dependencies | equality-generating dependencies | the chase algorithm query containment and rewriting under dependencies | data exchange | determinacy | XPath | tree dataDDC classification: 005.7565 Online resources: Abstract with links to full text | Abstract with links to resource Also available in print.| Item type | Current location | Call number | Status | Date due | Barcode | Item holds |
|---|---|---|---|---|---|---|
E books
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PK Kelkar Library, IIT Kanpur | Available | EBKE905 |
Mode of access: World Wide Web.
System requirements: Adobe Acrobat Reader.
Part of: Synthesis digital library of engineering and computer science.
Includes bibliographical references (pages 237-252).
1. Queries and views -- 1.1. Views -- 1.2. Using views in database systems -- 1.3. Answering queries using views -- 1.4. Relational databases and queries -- 1.5. The structure of the book -- 1.6. Exercises
2. Query containment and equivalence -- 2.1. CQ query containment -- 2.2. CQAC query containment -- 2.3. CQN query containment -- 2.4. CQA query containment and equivalence -- 2.5. Acyclic CQS -- 2.6. Query equivalence -- 2.7. Containment and equivalence for unions of queries -- 2.8. Exercises
3. Finding equivalent rewritings -- 3.1. Preliminaries -- 3.2. CQ queries and views -- 3.3. Acyclic Cq views -- 3.4. cqac queries and views -- 3.5. Rewriting Cqn queries using CQN views -- 3.6. cqa queries -- 3.7. Exercises
4. Maximally contained rewritings (MCRS) -- 4.1. Preliminaries -- 4.2. Finding MCRS for Cq queries and views: the MS algorithm -- 4.3. CQACs, the homomorphism property, extending algorithm MS -- 4.4. Datalog -- 4.5. Exercises
5. Answering queries in presence of dependencies -- 5.1. Preliminaries -- 5.2. Query containment under dependencies -- 5.3. Equivalent rewritings -- 5.4. MCRS -- 5.5. Exercises
6. Answering queries in data exchange -- 6.1. Complete data exchange -- 6.2. Data exchange with arithmetic comparisons -- 6.3. Incomplete data exchange -- 6.4. Exercises
7. Answering queries using views -- 7.1. Certain answers for queries in presence of view instances -- 7.2. Determinacy
8. XPath queries and views -- 8.1. Xml databases and XPath queries -- 8.2. XPath queries vs. Conjunctive queries -- 8.3. XPath query containment and equivalence -- 8.4. Definition of extended embedding between patterns -- 8.5. Containment test for XP{//,[]} and XP{[],*} -- 8.6. Extended embedding is not enough to prove containment -- 8.7. Canonical models -- 8.8. Containment for general case -- 8.9. Containment and equivalence of union of XPath queries -- 8.10. Rewritings -- 8.11. Conclusion and bibliographical notes -- 8.12. Exercises
9. Tree-structured records queried with SQL dialect -- 9.1. Trees as data and as data types -- 9.2. Querying tree-structured data -- 9.3. Flattening -- 9.4. Discussion: tree-pruning vs. flattening -- 9.5. Flattening for linear schemas -- 9.6. Aggregate queries -- 9.7. Conclusion and bibliographical notes
10. Bibliographical notes for chapters 1-7 -- 10.1. Query containment -- 10.2. Query rewriting -- 10.3. Dependencies--the chase -- 10.4. Data exchange -- 10.5. Other related work -- 11. Conclusion for chapters 1-7.
Abstract freely available; full-text restricted to subscribers or individual document purchasers.
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The topic of using views to answer queries has been popular for a few decades now, as it cuts across domains such as query optimization, information integration, data warehousing, website design and, recently, database-as-a-service and data placement in cloud systems. This book assembles foundational work on answering queries using views in a self-contained manner, with an effort to choose material that constitutes the backbone of the research. It presents efficient algorithms and covers the following problems: query containment; rewriting queries using views in various logical languages; equivalent rewritings and maximally contained rewritings; and computing certain answers in the data-integration and data-exchange settings. Query languages that are considered are fragments of SQL, in particular select-project-join queries, also called conjunctive queries (with or without arithmetic comparisons or negation), and aggregate SQL queries. This second edition includes two new chapters that refer to tree-like data and respective query languages. Chapter 8 presents the data model for XML documents and the XPath query language, and Chapter 9 provides a theoretical presentation of tree-like data model and query language where the tuples of a relation share a tree-structured schema for that relation and the query language is a dialect of SQL with evaluation techniques appropriately modified to fit the richer schema.
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