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Final Review

Final Review. Tuesday, March 6, 2007. The Final. Date: Tuesday, March 13, 2007 Time: 6:30 - 8:30 Room: EE 037 You must come to campus Open book exam :) No computers :(. Problem 1: Queries. SQL XPath/XQuery. SQL. Select-from-where Subqueries Aggregation Nulls Outer joins

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Final Review

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  1. Final Review Tuesday, March 6, 2007

  2. The Final • Date: Tuesday, March 13, 2007 • Time: 6:30 - 8:30 • Room: EE 037 • You must come to campus • Open book exam :) • No computers :(

  3. Problem 1: Queries • SQL • XPath/XQuery

  4. SQL • Select-from-where • Subqueries • Aggregation • Nulls • Outer joins • Database modifications (insert/delete) A tricky query: for each product, find total sales in November

  5. XPath/XQuery • Xpath: simple navigation /, //, *, […] • Xquery: nest/unnest/renest/aggregates A tricky query: eliminate duplicates in a collection of elements

  6. Problem 2: Data Modeling • E/R diagrams • Functional dependencies and normal forms • XML and semistructured data

  7. E/R Diagrams • Relationships • Inheritance • Weak entity sets • Mapping to relations • SQL DDL: • Creating tables • Constraints A tricky question: map a complex inheritance graph to relations

  8. Functional Dependencies • Basic definitions • Computing the closure X+ • Computing the keys • Checking if a relation is in BCNF • Decomposing into BCNF Tricky questions: find FD’s in a view; give counterexamples to FDs

  9. XML • XML syntax • DTD • From relations to XML • From XML to relations A tricky question: N/A

  10. Problem 3: Transactions • Recovery • Concurrency control

  11. Recovery • Undo log • Redo log • Undo/redo log A tricky question: place a missing END-CHECKPOINT

  12. Concurrency control • Serializability and conflict serializability • Locks • Timestamps • Validation A tricky question: tell what happens in a schedule

  13. Problem 4: Query Processing Engine • Storage of database elements • Indexes • Logical algebra • Physical algebra • Optimizations • Size/cost estimation

  14. Storage of Database Elements • Storing records in blocks • Storing attributes in records A tricky question: N/A

  15. Index Structures • Types of indexes: • Dense/sparse index • Primary/secondary index • B+-trees • Hash tables: • Extensible hash tables A tricky question: perform insert/delete in a B+ tree or hash table

  16. Logical Algebra • Operators • Some interesting ones: natural joins, semijoins • Converting SQL into the algebra A tricky question: SQL with NOT EXISTS to RA

  17. Physical Operators • One-pass algorithms • Nested-loop joins • Two-pass algorithms based on sorting • Two-pass algorithms based on hash tables • Index-based algorithms • Their cost A tricky question: N/A

  18. Optimizations • Algebraic laws • The dynamic programming algorithm • Pipelining A tricky question: discuss alternative plans for a query

  19. Size/Cost Estimation • Simple size estimation formulas for selection and join • Histograms • Eqdepth, eqwidth A tricky question: N/A

  20. General Advice • Some problems will require thinking • Use judgment • Problem difficulty may be uneven: • do the easy ones first

  21. Grading –Homework 35% –Project: 35% –Final: 30%

  22. COMMIT(The End)

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