Lecture8 - Prove that the basic two-phase locking protocol...

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Prove that the basic two-phase locking protocol guarantees conflict serializability of schedules. (Hint: Show that, if a serializability graph for a schedule has a cycle, then at least one of the transactions participating in the schedule does not obey the two-phase locking protocol.) Serializable schedule produces the same results as serial schedule. A schedule is serializable if it’s serializability graph is acyclic (no cycle). ------------------------------------------------------------------------------------------------------- According to Ozsu and Valduriez (1999), with the two-phase locking protocol, lock operation in the transaction doesn’t follow the unlock operation. Suppose that a schedule that obeys a two- phase locking rule is non conflict serializable. Then a serializability graph for that schedule has a cycle (Ozsu & Valduriez, 1999). As an example, we have transaction T1 and T2 with the following sequence of operations: [T1 (X), T2 (X)]; [T2(Y), T1(Y)] . The graph has a cycle
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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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Lecture8 - Prove that the basic two-phase locking protocol...

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