Query processing on uncertain data

Data uncertainty is pervasive in various fields, for example, economy, military, log istic, finance and telecommunication, etc. Uncertain data are inherent in some impo rtant applications, such as environmental surveillance, market analysis, Location-Based Service(LBS), and quantitative economics research. Due to the importance of those applications and the rapidly increasing amount of uncertain data collected and accumulated, querying large collections of uncertain data has become an impo rtant task and has received more and more attention from the database community in recent years. This paper introduces the principle of uncertain data query, and surveys the advance of the research on uncertain data query processing, including Nearest Neighbor(NN) query, Reverse Nearest Neighbor(RNN) query, Ranking query, top-k query and join query. By a detailed comparison, the pros and cons of the techn iques are discussed. In the end, the problems in current research and some future research issues are outlined.