Provided are a techniques for determining a frequency distribution for a set of records. A count table of frequency distributions is built in memory for each field in the set of records, wherein each record of each count table includes a field identifier, a field value, and a count of a number of times the field value occurs in the set of records, and wherein the field identifier concatenated with the field value comprises a composite key value. It is determined that at least one count table of frequency distributions is approaching a maximum amount of memory allocated to that count table. The records of the at least one count table that is approaching the maximum amount of memory are sent for sorting and additional counting, wherein the records include composite key values.