The salespeople always promise magic and handwave CAP away. But data at scale is about: 1) knowing your queries ahead of time (since you've presumably reached

The salespeople always promise magic and handwave CAP away. But data at scale is about: 1) knowing your queries ahead of time (since you've presumably reached the limit of PG/maybesql/o-rackle. 2) dealing with CAP at the application level: distributed transactions, eventual consistency, network partitions. 3) dealing with a lot more operational complexity, not less. So if the snake oil salesmen say it will be seamless, they are very very very much lying. Either that, or you are paying a LOT of money for other people to do the hard work. Which is what happens with managing your own NoSQL vs DynamoDB. You'll pay through the roof for DynamoDB at true big data scales.