  Due to the wide applications in recommendation systems, multi-class label
prediction and deep learning, the Maximum Inner Product (MIP) search problem
has received extensive attention in recent years. Faced with large-scale
datasets containing high-dimensional feature vectors, the state-of-the-art
LSH-based methods usually require a large number of hash tables or long hash
codes to ensure the searching quality, which takes up lots of index space and
causes excessive disk page accesses. In this paper, we relax the guarantee of
accuracy for efficiency and propose an efficient method for c-Approximate
Maximum Inner Product (c-AMIP) search with a lightweight iDistance index. We
project high-dimensional points to low-dimensional ones via 2-stable random
projections and derive probability-guaranteed searching conditions, by which
the c-AMIP results can be guaranteed in accuracy with arbitrary probabilities.
To further improve the efficiency, we propose Quick-Probe for quickly
determining the searching bound satisfying the derived condition in advance,
avoiding the inefficient incremental searching process. Extensive experimental
evaluations on four real datasets demonstrate that our method requires less
pre-processing cost including index size and pre-processing time. In addition,
compared to the state-of-the-art benchmark methods, it provides superior
results on searching quality in terms of overall ratio and recall, and
efficiency in terms of page access and running time.
