Dual-sorted inverted lists in practice

Abstract

We implement a recent theoretical proposal to represent inverted lists in memory, in a way that docid-sorted and weight-sorted lists are simultaneously represented in a single wavelet tree data structure. We compare our implementation with classical representations, where the ordering favors either bag-of-word queries or Boolean and weighted conjunctive queries, and demonstrate that the new data structure is faster than the state of the art for conjunctive queries, while it offers an attractive space/time tradeoff when both kinds of queries are of interest. © 2012 Springer-Verlag Berlin Heidelberg.