Practical Top-K Document Retrieval in Reduced Space

Supporting top-k document retrieval queries on general text databases, that is, finding the k documents where a given pattern occurs most frequently, has become a topic of interest with practical applications. While the problem has been solved in optimal time and linear space, the actual space usage is a serious concern. In this paper we study various reduced-space structures that support top-k retrieval and propose new alternatives. Our experimental results show that our novel algorithms and data structures dominate almost all the space/time tradeoff. ∗Partially funded by the Millennium Institute for Cell Dynamics and Biotechnology (ICDB), Grant ICM P05-001F, Mideplan, Chile; and by Fondecyt Grant 1-110066, Chile.