No statements will apply to all of anything, just thought I'd clarify since in ten years of working with nosql by large the largest deployments were with Mongo.

No statements will apply to all of anything, just thought I'd clarify since in ten years of working with nosql by large the largest deployments were with Mongo. Bad luck maybe :) There are reactive and non-reactive based SQL dbs too. I know someone at Amazon working on one. You can have state per connection and still use epoll or whatever. Even with NodeJS or Vertx you can open a connection against a worker pool, maintain state for that connection, and it doesn't require thread/process per connection. That's merely an implementation detail (and nice isolation for extensions etc).