Executing transactions in a distributed processing system

In order to execute transactions using computers (e.g. 1a, 1b) connected in a network, distribution arrangements are defined and stored in one computer (1a), which acts as a management computer. Each arrangement corresponds to a predetermined distribution of the transactions among the computers. One of the arrangements is distributed to all the computers, and transactions are executed on the basis of that arrangement. Subsequently, a further arrangement is distributed to the computers so that, when a suitable change-over condition occurs, the transactions may be executed on the basis of the further distribution arrangement The change-over condition may correspond to a particular time, failure of one of the computers, expansion of the network, or overload. In this way, the network may adapt to different circumstances without excessive processing being required.