I started with a multi-master Cassandra setup for my application, but I realized I don't need true multi-master functionality: I just need to be able to hide write latency by having applications write to a local slave instead of to the master. When the application does a read from that slave, they see their own writes, even if they haven't yet reached the master. Is there a KV store, relational DB, or column store that can do this?
My goal here with avoiding Cassandra is to: have a single master that can authoritatively resolve conflicts, hand out ranges of a 64-bit ID space to use instead of UUIDs, to get better local read and write performance, and to use far less memory.