Glossary · System coordination, integration and orchestration
Vector clock
Also known as: Vector timestamp
German: Vektoruhr
In distributed systems, a vector clock is a logical clock consisting of one counter per node that is attached to events and messages; comparing two vector clocks shows whether one event causally happened before the other or whether they are concurrent.
- System integration
In one sentence
A vector clock is a logical clock with one counter per node that shows whether events are causally ordered or concurrent.
Example
Two edge devices update the same configuration offline; when they reconnect, their vector clocks show that the updates were concurrent, so the system flags a conflict instead of silently overwriting one.
How it applies
- Engineering: Vector clocks are used to detect conflicting concurrent updates in replicated data stores and synchronization systems, independent of physical clock accuracy.
- Limits: The vector grows with the number of nodes, and vector clocks give only a partial order: concurrent events are detected but not ordered. A conflict resolution rule is still needed.
- Industrial context: Offline-capable systems, such as mobile maintenance apps or edge devices that sync later, benefit from causal conflict detection.
- Documentation: Where conflict detection affects users, for example in synchronized maintenance records, explain in the user documentation what a conflict means and how to resolve it.
Vector clock vs. physical timestamp
A physical Timestamp records when something happened according to a clock, which may be skewed. A vector clock records what a node knew when the event happened, which captures causality exactly but says nothing about real time. Systems often use both.