The proliferation of the World Wide Web has brought information retrieval (IR) techniques to the forefront of search technology. To the average computer user, “searching” now means using IR-based systems for finding information on the WWW or in other document collections. IR query evaluation methods and workloads differ significantly from those found in database systems. In this paper, we focus on three such differences. First, due to the inherent fuzziness of the natural language used in IR queries and documents, an additional degree of flexibility is permitted in evaluating queries. Second, IR queryevaluationalgorithms tend to haveaccesspatternsthat cause problems for traditional buffer replacement policies. Third, IR search is often an iterative process,in which a query is repeatedly refined and resubmitted by the user. Based on these differences, we developtwo complementarytechniquesto improve the efficiencyof IR queries: 1) Buffer-aware queryevaluation,which alters the q...