Faster Compressed Top-k Document Retrieval
Wing-Kai Hon, Sharma V. Thankachan, Rashid Rafiq Shah, Jeffrey Scott Vitter · 2013
Let D = {d1, d2,...dD} be a given collection of D string documents of total length n, our task is to index D, such that whenever a pattern P (of length p) and an integer k come as a query, those k documents in which P appears the most number of times can be listed efficiently. In this paper, we propose a compressed index taking 2|CSA| + D logn/D + O(D) + o(n) bits of space, which answers a query with O(tsalog k logϵn) per document report time. This improves the O(tsalog k log1+ϵn) per document report time of the previously best-known index with (asymptotically) the same space requirements [Belazzougui and Navarro, SPIRE 2011]. Here, |CSA| represents the size (in bits) of the compressed suffix array (CSA) of the text obtained by concatenating all documents in V, and tsais the time for decoding a suffix array value using the CSA.