If you shard a RethinkDB table to split it across multiple servers, and then create a changefeed on the table, the database will automatically send changes from both servers. Basically, server management/sharding in RethinkDB is visible to ops people, but is completely abstracted from the application developer. All writes are immediately consistent.
Rethink doesn't provide ACID guarantees, though. If you want to make a change to multiple documents in a table and have ACID guarantees, I'd stick with traditional RDBMSes.
How are all writes immediately consistent? What if two clients make simultaneous writes to each shard? Or more extreme, what if there is a net split and writes continue on both shards?
I suppose I could just ask if you have an architecture document floating around :)
If you shard a RethinkDB table to split it across multiple servers, and then create a changefeed on the table, the database will automatically send changes from both servers. Basically, server management/sharding in RethinkDB is visible to ops people, but is completely abstracted from the application developer. All writes are immediately consistent.
Rethink doesn't provide ACID guarantees, though. If you want to make a change to multiple documents in a table and have ACID guarantees, I'd stick with traditional RDBMSes.