Document Retrieval on Repetitive Collections?

Abstract. Document retrieval aims at finding the most important doc-uments where a pattern appears in a collection of strings. Traditional pattern-matching techniques yield brute-force document retrieval solu-tions, which has motivated the research on tailored indexes that offer near-optimal performance. However, an experimental study establish-ing which alternatives are actually better than brute force, and which perform best depending on the collection characteristics, has not been carried out. In this paper we address this shortcoming by exploring the relationship between the nature of the underlying collection and the per-formance of current methods. Via extensive experiments we show that established solutions are often beaten in practice by brute-force alterna-tives. We also design new methods that offer superior time/space trade-offs, particularly on repetitive collections.