So I looked around and found no viable solution for this problem: How to extract the most frequent terms in the search result set after submitting the query.
HighFreqTerms <http://lucene.apache.org/java/3_2_0/api/contrib-misc/index.html>and docFreq <http://lucene.apache.org/java/3_2_0/api/core/org/apache/lucene/index/FilterIndexReader.html#docFreq%28org.apache.lucene.index.Term%29>don't do the job for specific documents. - is it plausible to make a vector of resulted docID's and intersect it with each term's posting list in the index? bigger intersection meaning higher frequency. *because search results could be really custom, this method can't be optimize to intersect only the highest frequency terms for the entire index.
