1. A computer-implemented method for processing documents in a document database comprising: generating an initial ranking of retrieved documents using an information retrieval system and based upon a user search query; processing a plurality of vocabulary words based upon occurrences thereof in at least some of the retrieved documents; generating respective relevancies of the vocabulary words based on the occurrences thereof and the user search query; and generating a re-ranking of the retrieved documents based on the relevancies of the vocabulary words.