What is the 'happened-before' relationship and why does it matter?
Event A happened-before event B if A's vector is less-than-or-equal to B's vector (elementwise), and they differ. This proves A was in B's causal past—likely because A sent a message to B or through an intermediary. Respecting happened-before ensures consistency.
Answered in
Vector Clocks: Detecting Causality in Distributed SystemsVector clocks solve distributed ordering: when wall-clock timestamps fail to detect concurrent writes, vector clocks reveal true causality and conflicts.
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