[hinoglu]

Ops sorry, "replica" is the important part here.

There's no replica in the system. There are clients (clients of messaging system are sql servers) that are not realated to any other sql server in no means, which receive the same commands from a web application in the very same order each time.

Replication is lightweight and done in the sql proxy by replicating the messages, not in the sql servers. Simply it's a 1-1 connection between a web-app and sql-server, but the messages are multiplied by the number of sql-servers which made it a 1-N real time cloning system.