The quorum consensus replication algorithm requires that the timestamps of transactions be consistent with their commit order. In the absence of synchronized clocks, this requirement is not easily met. Propose an alternate algorithm for tagging replicas that can be used with quorum consensus. (Hint: Instead of assigning timestamps to transactions, assign version numbers to individual replicas.)

What will be an ideal response?


When an item is created, each replica is assigned the version number 0. When a transaction writes a new value to an item the new value of the version number of all the replicas in the set is one more than the maximum of all the old version numbers
in the set. Since read and write quorums intersect all write quorums, the replica with the maximum version number in any read quorum must have the most recent value of the item.

Computer Science & Information Technology

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What will be an ideal response?

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