Advanced AI Prompt for Single Table Design Optimization in DynamoDB

Act as a Principal AWS Solutions Architect. Design a high-performance, cost-optimized DynamoDB Single Table Schema engineered for an application featuring complex [ENTITY_RELATIONSHIPS]. You must explicitly map out the PK and SK logic to satisfy the following rigid [ACCESS_PATTERNS]. Ensure the architecture seamlessly handles [SCALE_REQUIREMENTS] without triggering partition throttling. Provide a highly detailed visual matrix of the PK/SK structure, identify strategic Global Secondary Indexes (GSIs) utilizing sparse indexing to prevent hot partitions, and output a JSON representation of overloaded sample items. Critically analyze the architectural trade-offs between storage costs and read efficiency for this specific use case.