cs411-s09-final-sol

cs411-s09-final-sol - CS411 Database Systems Spring 2009,...

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CS411 Database Systems Spring 2009, Prof. Chang Department of Computer Science University of Illinois at Urbana-Champaign Final Examination May 8, 2009 Time Limit: 180 minutes Problem 1 ( 32 points ) Misc. Concepts (1) False If two relations are both in BCNF, their join must also be in BCNF. (2) True Transaction management consists of two main functional components: concurrency control and failure recovery . (3) True SQL Injection attacks a Web site by manipulating the user input to cause harmful SQL commands to be executed at the backend database. (4) False Relational algebra was invented to formalize the underlying operations of the SQL language. (5) True When translating an E-R diagram to the relational model, there are multiple ways to translate a sub-class relationship. (6) False With respect to a set of integers, there exists a unique structure to index them in a B+ tree. (7) True In determining a query plan involving joins, by focusing on only left-deep join trees, we are not guaranteed to generate the optimal query plan. (8) True Regardless of UNDO or REDO, a logging system must write the corresponding log entry before any update of database values on disk. (9) False In cost-based optimization, dynamic programming is a technique that helps us to estimate the cost of a query plan. 1
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Figure 1: E-R diagram (10) True For the same operations ( e.g. , sorting, grouping), two-pass algorithms generally require less memory buffer than their corresponding one-pass algorithms. (11) True An important requirement for database indexing is the ability of the index to maintain an appropriate structure as the database changes over time. (12) False The Explain Plan facility in Oracle SQL shows the execution plan and its actual cost by executing the plan.
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cs411-s09-final-sol - CS411 Database Systems Spring 2009,...

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