title: Finding total number of matches to a query with lucene
body: <p>I'm new to lucene so I don't know if it is possible, but I have an index and I would like to get the total amount of phrases in a subset of the index(the subset is defined by a filter).
  I can use FilteredQuery with my Filter and a PhraseQuery to search for the phrase and thus I can count the documents in which this phrase occurs, but I can't seem to find a way to count the number of matches per document as well.</p>