I always thought SaaS are based shardig, load balance and multiple-tenant. In the past several days, I re-read Dynamo and DynamoDB papers to figure out some key info to share with my colleages to find a common ground about DynamoDB. One thing is mentioned many times in DynamoDB is token-bucket. Suddenly a thought popped out my mind when I walked back after lunch with my colleague that token-bucket algorithm should be a component of SaaS and multiple-tenant.