How to migrate from legacy relational databases

We've got lots of legacy databases, we've got NoSQL databases, we've got NewSQL databases but how do we find the best one to help our enterprise transition from legacy on-prem relational databases to that brave new world in the cloud with their next generation distributed, NoSQL applications? How do you do that smoothly, securely, with performance and scale? It's a difficult journey so we've got Peter Finter, CMO of Couchbase to give us his thoughts with Mike Matchett of Small World Big Data.