---Ch20Ans - CS 501 Chapter 20 Transaction Management Page...

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Unformatted text preview: CS 501 Chapter 20 Transaction Management Page 1 of 3 Page 628 20.18 For each of the following schedules, state whether the schedule is serializable, conflict-serializable, view- serializable, recoverable, and whether it avoids cascading aborts: (a) read(T 1 , bal x ), read(T 2 , bal x ), write(T 1 , bal x ), write(T 2 , bal x ), commit(T 1 ), commit(T 2 ) Not (conflict) serializable; not view serializable. Recoverable; avoids cascading abort. (b) read(T 1 , bal x ), read(T 2 , bal y ), write(T 3 , bal x ), read(T 2 , bal x ), read(T 1 , bal y ), commit(T 1 ), commit(T 2 ) Conflict serializable and so view serializable. Recoverable; (however, does not avoid cascading abort if T 3 had aborted, T 2 would also have to abort as it has read the value of an aborted transaction). (c) read(T 1 , bal x ), write(T 2 , bal x ), write(T 1 , bal x ), abort(T 2 ), commit(T 1 ) Assuming abort occurs, then only transaction T 1 occurs making schedule serial and thus conflict serializable and view serializable. Without abort, then not (conflict) serializable; not view serializable. serializable and view serializable....
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---Ch20Ans - CS 501 Chapter 20 Transaction Management Page...

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