What systems actually use vector clocks in production?
Dynamo-style databases (Amazon DynamoDB, Cassandra), distributed version control (Git uses similar logic), and any last-write-wins store with eventual consistency. They're not used everywhere because read-only queries don't need them; they're essential only when writes race across multiple nodes.
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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