Using query transformation to improve Gnutella search performance

Abstract—Gnutella peers independently choose the way in which objects are named as well as queried. Using a long term analysis of the files shared and queries issued, we show that this flexibility leads to a mismatch between the way that objects were named and the way that users were issuing search queries. Thirty percent of the failed queries contained keywords that were not present in any file name while the remaining queries failed because no file name contained all the keywords in a particular query. Our earlier analysis of files shared in the popular iTunes music file sharing system showed that standardizing the file names to make them easier to search is not a viable alternative. Instead, we transform the queries to better match the objects available in the system. We investigated spell correction (using file name information from the neighborhood) as well as remove query keywords. We consider the results from the transformed query to be relevant to the intent of the original query if the transformed query used many of the original keywords and the number of matching files closely matched the number of matches for typical successful queries. Our approach is practical and uses information available within the immediate neighborhood of an ultra-peer. An overlay agnostic analysis shows that our transformation improves success rates from 45 % to between 72.5 % and 91.2%. Using our Hybrid mechanism as a Gnutella middleware, our transformation produced relevant results for about 61 % of the failed queries. Keywords-unstructured peer-to-peer, query transformation I