[chrisduesing]

As I mentioned the code that writes the event to the db notifies the client about it, so it knows about the client. This isn't really an issue.

In the case of an exchange I never split a single order book across multiple servers, but I can imagine a lot of applications where this could be an issue. How do you handle data consistency across nodes? Ultimately you have to solve the same issue...

Again, this isn't a big limitation for my use case. That said your answer has certainly given me a greater understanding of other circumstances where it would be very useful. Thank you.

[coffeemug]

Fellow finance engineer!

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.

[chrisduesing]

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 :)