Comment by dalailambda

While the move seems to be towards NewSQL databases (Spanner/CockroachDB), the answer to relations in NoSQL is to model the data differently. This can generally resolve a lot of the problems inherent in the need for relations.

This might not be useful advice for everyone, but I can highly recommend this youtube video on DynamoDB data modelling: https://www.youtube.com/watch?v=HaEPXoXVf2k