Engineering Efficient and Effective Non-metric Space Library

We present a new similarity search library and discuss a variety of design and performance issues related to its development. We adopt a position that engineering is equally important to design of the algorithms and pursue a goal of producing realistic benchmarks. To this end, we pay attention to various performance aspects and utilize modern hardware, which provides a high degree of parallelization. Since we focus on realistic measurements, performance of the methods should not be measured using merely the number of distance computations performed, because other costs, such as computation of a cheaper distance function, which approximates the original one, are oftentimes substantial. The paper includes preliminary experimental results, which support this point of view. Rather than looking for the best method, we want to ensure that the library implements competitive baselines, which can be useful for future work.