Optimistic-CC - Distributed Optimistic Algorithm...

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Optimistic-CC Distributed Optimistic Algorithm Assumptions 1. Synchronized clocks 2. MTD (max, trans, delay) can be defined Step 1: same as before Step 2: same as before Step 3: transaction is broadcasted to all nodes at time π (V i ) (time when computation finishes and T i is ready for validation) Step 4: At time π (V i ) + MTD, all nodes start validation of T i . (Note π (V i ) is attached to T i ) and if T i reaches before π (V i ) + MTD, it must wait
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Optimistic-CC Step 5: If validation succeeds, all nodes write S(w i ) ELSE all nodes except “X” ignore T i At node X, T i is restarted and repeated until T i validates THEOREM: The dist. opt. algorithm produces only correct histories at each node and all histories are identical PROOF: ONLY correct histories are produced. Because of Theorem 1 ELSE UPDATE S(R i ) and repeat from step 2
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Optimistic-CC CASE 2: Validation takes place at local node and then at central node 1. Same 2. Same 3. T i validates at X 4. If successful, T i commits at X and is sent to C ELSE UPDATE S(R i ) and repeat from step 2 1. If successful at C, send write set to all nodes ELSE UPDATE S(R i ) at C and execute at C and repeat validation until successful.
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Optimistic-CC Centralized Optimistic Algorithm: A node(C) is chosen as central node CASE 1: Validation takes place only at central node When T i arrives at a node “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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Optimistic-CC - Distributed Optimistic Algorithm...

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