1. A computer implemented method comprising: providing a distributed map that resides on a plurality of devices that maps data from a first dimension level in a hierarchy to a second dimension level in the hierarchy, wherein the data comprises a plurality of data items each associated with an identifier and the distributed map is partitioned into a plurality of portions and each portion resides on one of the plurality of devices; for each data item, sending a request to a particular one of the plurality of devices to obtain a particular portion of the distributed map that maps the data item from the first dimension level to the second dimension level, wherein the request is sent to the particular device based on the identifier associated with the data item; and aggregating data from the first dimension level to the second dimension level based on the mapping.