Systems, methods, and other embodiments are disclosed for performing data mining. In one embodiment, transaction records are read one at a time. Each transaction record represents a transaction for at least one item and includes an item identifier and a metric value for the item. The number-of-occurrences of at least one candidate item set in the transaction records are counted to generate a total count for the candidate item set. The candidate item set includes one or more items. As the counting proceeds, at least one aggregate metric value associated with the candidate item set is accumulated by summing metric values across the number-of-occurrences for each item represented in the candidate item set. A determination is made as to whether the candidate item set is a frequent item set in the transaction records by comparing the total count to a threshold value.