Methods, systems, and computer program products for determining frequently occurring data items are disclosed. These include, counting distinct categories of a plurality of data items using an ordered set of counters, wherein each of the counters is associated with one of the distinct categories and represents a quantity of the data items in the associated one of the distinct categories, and wherein the counting includes updating counters in the ordered set and a global decrement counter when one of the data items fails to match at least one of the distinct categories associated with the counters of the ordered set and when the ordered set is full. These further include, reporting, for each of the counters in the ordered set, a lower bound for the associated one of the distinct categories, wherein the lower bound is based upon a value of the counter and the global decrement counter.