Query routing for Web search engines: architecture and experiments

General-purpose search engines such as AltaVista and Lycos are notorious for returning irrelevant results in response to user queries. Consequently, thousands of specialized, topic-specific search engines (from VacationSpot.com to KidsHealth.org) have proliferated on the Web. Typically, topic-specific engines return far better results for “on topic” queries as compared with standard Web search engines. However, it is difficult for the casual user to identify the appropriate specialized engine for any given search. It is more natural for a user to issue queries at a particular Web site, and have these queries automatically routed to the appropriate search engine(s). This paper describes an automatic query routing system called Q-Pilot. Q-Pilot has an off-line component that creates an approximate model of each specialized search engine’s topic. On line, Q-Pilot attempts to dynamically route each user query to the appropriate specialized search engines. In our experiments, Q-Pilot was able to identify the appropriate query category 70% of the time. In addition, Qpilot picked the best search engine for the query, as one of the top three picks out of its repository of 144 engines, about 40% of the time. This paper reports on Q-pilot’s architecture, the query expansion and clustering algorithms it relies on, and the results of our preliminary experiments.