1. I know it's open-source, but they have a `citus-mx` product which has multiple masters which isn't open-source (currently you have to do coordinators manually).
2. Kind hard to creep up on scylladb by seeing it's architecture and assuming you use it for what it's best at, the asyncness and raw performance.
https://github.com/citusdata/citus
Which is why Postgres is creeping up on both scylladb and cassandra.
Plus PG 10 will have declarative partitioning built in. Pretty cool.