Filler · 0.2s
That’s a good question — let me walk you through how I’d think about it from first principles.
Answer · streaming
I’d use DynamoDB global tables with last-writer-wins on the claim-status field. We measured the contention window at under two seconds at Anthem. For anything stronger, we fall back to a Saga with compensating transactions — 180 ms more p99, but it gives auditors the correctness story they want.
Follow-up · cached
If Alex asks about failure modes: Kinesis shard hot-spotting during open-enrollment spikes. Mitigation: consistent hashing plus a dynamic resharder.