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cop5615fa11quiz5key - RM2 and RM3 The initial values for V...

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Quiz 5 Key COP 5615 Fall 2011 1) a) What is the main difference between the standard Timestamp Protocol for transactions and the Banzai Timestamp Protocol? b) What are the potential consequences of this difference? Answer: a) The Banzai TSP does not do tentative writes nor does it delay reads – all actions either take place immediately or the transaction aborts. b) Since a write may occur that is seen by another transaction, and the the writing transaction may abort, the system may have cascading aborts. This also means that the TID of all reading transactions of an object must be stored, even after they “commit.” 2) Observe the time-space diagram below, with three Replica Managers, RM1,
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Unformatted text preview: RM2, and RM3. The initial values for V and R are 000 for all three RMs in the Causal Consistency Gossip Update protocol. a) Show the values of V, R, and the log at each RM at point A. Explain. b) Repeat (a) at point B. Answer: (r1=100,u1=000); (r2=110,u2=100); (r3=001,u3=000), (r4=200,u4=200) a) V1=100, R1=200, L1 includes u1 and u4 only (both applied) V2=000, R2=110, L2 includes u2 only (delayed) V3=001, R3=001, L3 includes u3 only (applied) b) V1=100, R1=200, L1 includes u1 and u4 only (both applied) V2=210, R2=210, L2 includes u1, u2, and u4 only (all applied) V3=211, R3=211, L3 includes all updates, all applied...
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