Distribution-aware compressed full-text indexes

In this paper we address the problem of building a compressed self-index that, given a distribution for the pattern queries and a bound on the space occupancy, minimizes the expected query time within that index space bound. We solve this problem by exploiting a reduction to the problem of finding a minimum weight K-link path in a properly designed Directed Acyclic Graph. Interestingly enough, our solution can be used with any compressed index based on the Burrows-Wheeler transform. Our experiments compare this optimal strategy with several other known approaches, showing its effectiveness in practice.