Similarity calculations and document ranking form the computationally expensive parts of query processing in ranking-based text retrieval. In this work, for these calculations, 11 alternative implementation techniques are presented under four di?erent categories, and their asymptotic time and space complexities are investigated. To our knowledge, six of these techniques are not discussed in any other publication before. Furthermore, analytical experiments are carried out on a 30 GB document collection to evaluate the practical performance of di?erent implementations in terms of query processing time and space consumption. Advantages and disadvantages of each technique are illustrated under di?erent querying scenarios, and several experiments that investigate the scalability of the implementations are presented.
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