Final Exam 2010

Circle the attributes sets that are candidate keys

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Unformatted text preview: 3 SID: ____________________________ Q2: Normal Forms [11 points] Consider the “Congress” relation, and associated functional dependencies: Congress(Bill, Title, Sponsor, Party, District, Committee, cHairperson, chAirperson_party, heaRing_time) R → SP SP → DCH B → SCT DH → A TS → R SPR → B S → P a) [4 points] All of the candidate keys for the relation above are listed below, possibly along with some attribute sets that are not candidate keys. Circle the attributes sets that are candidate keys for the relation above.  ­ R  ­ S  ­ B  ­ TS b) Circle the constraints below (if any) that violate BCNF. [4 points] 1. R → SP 2. SP → DCH 3. B → SCT 4. DH → A 5. TS → R 6. SPR → B 7. S → P 8. None of the above c) Consider the following relation and functional dependencies: SupremeCourt(Docket, Appellant, Respondent, Oral_argument_time, oPinion_author, appoInted_by, parTy) 1. PI → T 2. RP → I 3. O → ARP 4. D → O 5. OA → D i) Write the lossless ­join decomposition of this relation into BCNF, by resolving the constraints that violate BCNF (if any) in numerical order. [2 points] ii) Is this decomposition dependency ­preserving? [1 point] 4 SID: ____________________________ d) Assume that you considering a new normal form TANF (Totally Awesome Normal Form). A constraint satisfies TANF for a relation R if, for every functional dependency X → Y, one of the following is true: i) X → Y is a trivial FD ii) X is a candidate key for R Assume you decompose a relation R into TANF in the same way you decompose a relation into BCNF. Does this decomposition for TANF always have the lossless ­join property? If yes, provide a 2.5 ­line argument. If no, provide a counterexample involving at most two FDs. Longer answers will receive no credit. [3 points] If YES, write argument here: _____________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________ If NO, write counterexample here: 5 SID: ____________________________ Q3: Concurrency [10 points] Consider the following schedule of accesses by three transactions. The labels R and W indicate reads and writes, and the labels A, B, and C indicate distinct elements of data. Time 1 2 3...
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