Departmental Papers (CIS)

Date of this Version

October 2003

Document Type

Technical Report


University of California, Berkeley Department of Electrical Engineering and Computer Sciences Technical Report No. CSD-03-1277.
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NOTE: At the time of publication, author Boon Thau Loo was affiliated with the University of California at Berkeley. Currently (April 2007), he is a faculty member in the Department of Computer and Information Science at the University of Pennsylvania.


Unstructured Networks have been used extensively in P2P search systems today primarily for file sharing. These networks exploit heterogeneity in the network and offload most of the query processing load to more powerful nodes. As an alternative to unstructured networks, there have been recent proposals for using inverted indexes on structured networks for searching. These structured networks, otherwise known as distributed hash tables (DHTs), guarantee recall and are well suited for locating rare items. However, they may incur significant bandwidth for keyword-based searches. This paper performs a measurement study of Gnutella, a popular unstructured network used for file sharing. We focus primarily on studying Gnutella's search performance and recall, especially in light of recent ultrapeer enhancements. Our study reveals significant query overheads in Gnutella ultrapeers, and the presence of queries that may benefit from the use of DHTs. Based on our study, we propose the use of a hybrid search infrastructure to improve the search coverage for rare items and present some preliminary performance results.



Date Posted: 05 April 2007