Useful 'middle' consistency models that match user expectations cheaply.
Read-Your-Writes, Monotonic, Causal: useful 'middle' consistency models that match user expecta...
choose the failure mode you can explain
Sticky routing is simple but uneven load.
Between linearizable and eventual sit useful guarantees: read-your-writes (you see your own write), monotonic reads (no time travel backwards), and causal consistency (effects follow causes). They're cheap and they fix most user-visible 'why is my edit gone' bugs.
Read-your-writes: route the same user's reads to the replica that has their writes, or use a version token.
Monotonic reads: pin sticky-replica or pass max-seen version.
Causal: track 'happens-before' (vector clocks, lamport timestamps); rare in app code, common in some stores.
User edits profile but next page-load shows old data.