A first request to access a first set of items is received, wherein each item is associated with one or more properties. A second request to access a second set of items is also received. A determination is made as to whether items from the first set are in the second set of items, and the sets are divided into one or more subsets based on the determining. Each of the one or more subsets is assigned to a respective thread, and the respective thread of the subset that does not contain items in the second request is processed. This way, individual subsets (i.e. data partitions) can be processed by multiple threads in parallel without having to synchronize them.