Title
Efficient Neural Ranking using Forward Indexes
Abstract
ABSTRACT Neural document ranking approaches, specifically transformer models, have achieved impressive gains in ranking performance. However, query processing using such over-parameterized models is both resource and time intensive. In this paper, we propose the Fast-Forward index – a simple vector forward index that facilitates ranking documents using interpolation of lexical and semantic scores – as a replacement for contextual re-rankers and dense indexes based on nearest neighbor search. Fast-Forward indexes rely on efficient sparse models for retrieval and merely look up pre-computed dense transformer-based vector representations of documents and passages in constant time for fast CPU-based semantic similarity computation during query processing. We propose index pruning and theoretically grounded early stopping techniques to improve the query processing throughput. We conduct extensive large-scale experiments on TREC-DL datasets and show improvements over hybrid indexes in performance and query processing efficiency using only CPUs. Fast-Forward indexes can provide superior ranking performance using interpolation due to the complementary benefits of lexical and semantic similarities.
Year
DOI
Venue
2022
10.1145/3485447.3511955
International World Wide Web Conference
Keywords
DocType
Citations 
retrieval, dense, sparse, ranking, interpolation
Conference
0
PageRank 
References 
Authors
0.34
0
5
Name
Order
Citations
PageRank
Jurek Leonhardt100.34
Koustav Rudra252.62
Megha Khosla3186.01
Abhijit Anand400.68
Avishek Anand501.01