1. For a controller of a distributed network control system comprising a plurality of controllers for managing forwarding elements that forward data in a network, a method for managing the forwarding elements, the method comprising: changing a set of data tuples stored in a relational database of the first controller that stores data tuples containing data for managing a set of forwarding elements; and sending the changed data tuples to at least one of other controllers of the network control system, wherein the other controller receiving the changed data tuples processes the changed data tuples and sends the processed data tuples to at least one of the managed forwarding elements.