Why can't we just use wall-clock timestamps to order events across machines?
Clock skew is inevitable in distributed systems. Two machines' clocks drift by milliseconds or seconds, so an event that happens LATER can receive an EARLIER timestamp. Last-write-wins databases relying on timestamps will silently discard the newer write and lose data.
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.
Read the full analysisOther questions this article answers
More system design questions
- Why doesn't Google just run Dijkstra faster?
- What is a shortcut edge and when is it precomputed?
- How much space do shortcut edges take compared to the original graph?
- Can Contraction Hierarchies handle dynamic graphs like traffic or road closure?
- Why contract low-degree nodes first instead of high-degree ones?
- What is a CRDT and why does it matter for real-time collaboration?
- How do CRDTs handle concurrent edits without a central server referee?
- Why did Figma move from operational transforms to CRDTs?
Every answer on Crashtech is written by the editor of the article it comes from — never auto-summarised. Browse all answers or the System Design beat.