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