transaction including a plurality of operations each operation for applying to a data item each operation having a reliability level associated therewith each transaction is divided into one or more sub transactions based upon reliability level of the operations sub transactions are then dispatched to a persistence manager for execution against a persistent store application_number US 26007605 A description in accordance with a preferred embodiment there is provided a technique for managing transactions which comprise operations on multiple data items spanning more than one reliability level the functionality to achieve this may be built into a data manager fig2 shows a data processing system including the data manager in accordance with a preferred embodiment of the present invention fig3 illustrates the processing of the present invention in accordance with a preferred embodiment fig2 and 3 should be read in conjunction with one another data processing system 100 receives a request from an application at step 200 the request is passed to data manager 120 step 210 and mapping component 125 maps the request into the operations necessary to achieve the application 39 s request step 220 each transaction is then passed to analyzer component 130 analyzer component 130 analyses each transaction to determine the data items data 160 being operated on and the reliability levels associated with each such data item step 230 having performed the necessary analysis this information is passed to transaction manipulator component 140 which divides each transaction into sub transactions based on the reliability level of the data items involved step 240 such subtransactions are then passed to dispatcher 150 which passes these to persistence manager 60 step 250 the reliability level associated with a sub transaction determines the nature of interaction by the persistence manager 60 with the persistent store.