ex8 - Exercise 08 17.14 Change transaction T 2 in Figure...

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Exercise # 08 17.14 Change transaction T 2 in Figure 17.2b to read: read_item(X); X:= X+M; if X > 90 then exit else write_item(X); Discuss the final result of the different schedules in Figure 17.3 where M = 2 and N = 2, with respect to the following questions. Does adding the above condition change the final outcome? Does the outcome obey the implied consistency rule (that the capacity of X is 90)? 17.15 Repeat Exercise 17.14 adding a check in T 1 so that Y does not exceed 90. 17.20 Why is an explicit transaction end statement needed in SQL but not an explicit begin statement? 17.21 Describe situations where each of the different isolation levels would be useful for transaction processing. 17.22 Which of the following schedules is (conflict) serializable? For each serializable schedule, determine the equivalent serial schedules. (a) r1 (X); r3 (X); w1(X); r2(X); w3(X) (b) r1 (X); r3 (X); w3(X); w1(X); r2(X) (c) r3 (X); r2 (X); w3(X); r1(X); w1(X) (d) r3 (X); r2 (X); r1(X); w3(X); w1(X)
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This note was uploaded on 12/23/2009 for the course DBST 663 taught by Professor Tba during the Spring '09 term at MD University College.

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ex8 - Exercise 08 17.14 Change transaction T 2 in Figure...

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