PROFILING DATA WITH SOURCE TRACKING

Profiling data includes accessing multiple collections of records to store quantitative information for each particular collection including, for at least one selected field of the records in the particular collection, a corresponding list of value count entries, each including a value appearing in the selected field and a count of the number of records in which the value appears. Processing the quantitative information of two or more collections includes: merging the value count entries of corresponding lists for at least one field from each of a first collection and a second collection to generate a combined list of value count entries, and aggregating value count entries of the combined list of value count entries to generate a list of distinct field value entries identifying a distinct value and including information quantifying a number of records in which the distinct value appears for each of the two or more collections.