QUERYING A DATA STORE OF IMPRESSIONS

Systems, methods and computer program products identify a plurality of webpage attributes, where each of the plurality of webpage attributes is associated with a value. A date tree is built, the data including a plurality of nodes identifying the values associated with the plurality of webpage attributes, and is optimized by deleting one or more of the plurality of nodes. The number of web pages associated with at least one of the plurality of nodes in the optimized data tree is then determined.