This is the last day of Week 6. DynamoDB is the service generating the most questions on DVA-C02. Simple memorization doesn't survive variant problems. In this day, we connect partition key design mathematics, read consistency models, LSI/GSI internal differences, DAX cache layer, Streams + Lambda integration, transaction 2PC, and TTL async deletion into one architecture map, concluding with full-exam-style comprehensive problems. Those viewing DynamoDB "from the perspective of how data is stored and read at partition level" versus those "memorizing only API names" get completely different exam results on the same problem.