Recurrent Binary Embedding for GPU-Enabled Exhaustive Retrieval from Billion-Scale Semantic Vectors

TL;DR

This paper introduces Recurrent Binary Embedding (RBE), a novel model enabling efficient billion-scale exhaustive retrieval on GPUs by refining binary vectors for high accuracy, significantly improving over previous binary and full-precision models.

Contribution

The paper presents RBE, a new binary embedding model with a residual refinement process, and an end-to-end GPU system for real-time billion-scale retrieval, outperforming existing models.

Findings

RBE outperforms state-of-the-art binary models in AUC.

RBE narrows the accuracy gap with full-precision models by over 80%.

The system achieves real-time retrieval from over a billion candidates.

Abstract

Rapid advances in GPU hardware and multiple areas of Deep Learning open up a new opportunity for billion-scale information retrieval with exhaustive search. Building on top of the powerful concept of semantic learning, this paper proposes a Recurrent Binary Embedding (RBE) model that learns compact representations for real-time retrieval. The model has the unique ability to refine a base binary vector by progressively adding binary residual vectors to meet the desired accuracy. The refined vector enables efficient implementation of exhaustive similarity computation with bit-wise operations, followed by a near- lossless k-NN selection algorithm, also proposed in this paper. The proposed algorithms are integrated into an end-to-end multi-GPU system that retrieves thousands of top items from over a billion candidates in real-time. The RBE model and the retrieval system were evaluated with data from a major paid search engine. When measured against the state-of-the-art model for binary representation and the full precision model for semantic embedding, RBE significantly outperformed the former, and filled in over 80% of the AUC gap in-between. Experiments comparing with our production retrieval system also demonstrated superior performance. While the primary focus of this paper is to build RBE based on a particular class of semantic models, generalizing to other types is straightforward, as exemplified by two different models at the end of the paper.