Definition
Plain language
A guarantee in a distributed database that if one event could have caused another, every observer sees them in that order.
As stated in the literature
A weak distributed-systems consistency model ensuring that operations causally related (via reads-from or program-order) are observed in causal order at all replicas, used as the correctness spec for the Chapar key-value store.
Why it matters: It's a sweet spot for distributed systems: stronger than eventual consistency, but cheap enough to implement at scale, making it a common correctness target.
For example, if Alice posts a message and Bob replies, causal consistency guarantees no replica ever shows Bob's reply before Alice's original post.
Heard on the show
“The benchmark is Chapar, which is a verified key-value store that gives a property called causal consistency.”Episode 075 — Growing Code and Proof Together: Verified Systems in Ten Hours Instead of a Year