The invention is directed towards a database access coordination arrangement (23) in a federated database system (10) comprising applications (Ai, A2, A3) that access databases (34-50) under the control of a number of query handlers (24-32), the database access coordinating arrangement providing a group of traffic distribution units (16-22), each having connections to corresponding query handlers, and a traffic control unit (TCU), which traffic control unit selects traffic distribution unit for a query (Qi) from an application (Ai) based on at least one connectivity map of the connections existing between traffic distribution units, query handlers and databases and connectivity states of connections between traffic distribution units and query handlers, and schedules the query to the selected traffic distribution unit for accessing a database.