5 / 10 Clocks, Ordering & Causality

The Write That Vanished

Two replicas accept writes to the same key and resolve conflicts by last-write-wins on wall-clock timestamps. Replica A's clock runs 400 ms ahead of replica B's. A user writes through A, then 200 ms later writes again through B, and the second write is the one that disappears. What is happening?

A

The replicas disagreed on the key's version counter, so anti-entropy repair rolled the key back to its last common version

B

The 200 ms gap is shorter than the replication interval, so anti-entropy repair later restored the version that had already propagated to both replicas

C

The earlier write was stamped by the fast clock, so it carries the larger timestamp and overwrites the update that actually happened later

D

Both writes carry equal timestamps at millisecond resolution, so the store keeps whichever version has the lexicographically larger value