Version vector

Version vector is a mechanism that generates a pre-order in a distributed system. It enables causality tracking among data replicas and is a basic mechanism for optimistic replication. The state in a version vector is identical to the state in a vector clock but with diferent update rules:

• Initially all vector counters are zero.
• Each time a replica experiences an update event, it increments its own counter in the vector by one.
• Each time two replicas synchronize, both resulting vectors are identical and will depict the pairwise maximum between the two vectors across all counters.