[DynamoDB] DynamoDB as Session State Cache

It's common to use DynamoDB to store session state

• auto scaling feature

vs ElastiCache:

• ElasitCache is in-memory, but DynamoDB is serverless
• Both are key/value store

vs EFS:

• EFS must be attached to EC2 instances as a network drive

vs EBS & Instance Store:

• EBS & Instance Store can only be used for local caching, not shared caching

vs S3: not a good option, higher latency