Single stream partition throttles DynamoDB
DynamoDB table keyed on `streamId` (partition key) + `ts` (sort key) storing live-stream chat events. During a single huge livestream, the app starts getting `ProvisionedThroughputExceededException` / throttling on writes for that stream while overall table-level consumed capacity is well under the provisioned total. CloudWatch shows one partition's throttle count spiking; everything else is fine. The stream has 5M concurrent viewers chatting. Triage, mitigate live, and redesign so it can't recur.
What a strong answer looks like
Stop the bleeding first (mitigate), then form hypotheses from real signals. Separate root cause from symptom, communicate status as you go, and close with what prevents a repeat.
0:00 of about 35 min
Which questions mattered is sealed until you submit. Telling you now would just be handing over the edge cases.
Run or narrate your approach, then ask the coach.