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2010 IEEE 26th International Conference on Data Engineering (ICDE 2010) (2010)
Long Beach, CA, USA
Mar. 1, 2010 to Mar. 6, 2010
ISBN: 978-1-4244-5445-7
pp: 365-376
Akrivi Vlachou , Department of Computer Science, NTNU, Trondheim, Norway
Christos Doulkeridis , Department of Computer Science, NTNU, Trondheim, Norway
Yannis Kotidis , Department of Informatics, AUEB, Athens, Greece
Kjetil Norvag , Department of Computer Science, NTNU, Trondheim, Norway
Rank-aware query processing has become essential for many applications that return to the user only the top-k objects based on the individual user's preferences. Top-k queries have been mainly studied from the perspective of the user, focusing primarily on efficient query processing. In this work, for the first time, we study top-k queries from the perspective of the product manufacturer. Given a potential product, which are the user preferences for which this product is in the top-k query result set? We identify a novel query type, namely reverse top-k query, that is essential for manufacturers to assess the potential market and impact of their products based on the competition. We formally define reverse top-k queries and introduce two versions of the query, namely monochromatic and bichromatic. We first provide a geometric interpretation of the monochromatic reverse top-k query in the solution space that helps to understand the reverse top-k query conceptually. Then, we study in more details the case of bichromatic reverse top-k query, which is more interesting for practical applications. Such a query, if computed in a straightforward manner, requires evaluating a top-k query for each user preference in the database, which is prohibitively expensive even for moderate datasets. In this paper, we present an efficient threshold-based algorithm that eliminates candidate user preferences, without processing the respective top-k queries. Furthermore, we introduce an indexing structure based on materialized reverse top-k views in order to speed up the computation of reverse top-k queries. Materialized reverse top-k views trade preprocessing cost for query speed up in a controllable manner. Our experimental evaluation demonstrates the efficiency of our techniques, which reduce the required number of top-k computations by 1 to 3 orders of magnitude.

C. Doulkeridis, K. Norvag, Y. Kotidis and A. Vlachou, "Reverse top-k queries," 2010 IEEE 26th International Conference on Data Engineering (ICDE 2010)(ICDE), Long Beach, CA, USA, 2010, pp. 365-376.
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