A Brief Introduction to the ScaNN Index

Introduces the ScaNN index, detailing its two key innovations: a score-aware quantization objective that preserves the relative ordering of true neighbors and FastScan, a SIMD-optimized 4-bit PQ lookup path for reduced memory bottlenecks. Provides experimental results demonstrating ScaNN's performance advantages over IVFFLAT and IVF_PQ in terms of QPS and memory footprint, particularly when raw data is not loaded.