Vector clocks order concurrent writes
Each node keeps a counter per participant. Comparing vectors reveals a causal edge or a true concurrent write, which decides whether to merge or to ask. One timestamp is not enough A single timestamp cannot order concurrent events, because a clock is not a cause, so two nodes that each wrote something at the same label may still disagree about which came first. Vector clocks solve that by giving every participant its own counter: a process bumps its own slot whenever it does something, and merges the sender’s vector into its own whenever it receives a message. The result is a vector that grows as events happen, and comparing two vectors tells you whether one event provably preceded the other, or whether neither did. ...