25. The system of claim 24 wherein the join engine is further configured to rank each of the identified documents from the primary result sets and the secondary result sets that have common field values as a function of at least the combined score.
26. The system of claim 25 wherein the search engine is further configured to retrieve and present the at least a subset of the identified documents from the primary result sets and the secondary result sets that have common field values in a list of results on a display according to the ranking.