Definition
Hierarchical Navigable Small World (HNSW) is a graph-based approximate nearest neighbor (ANN) search algorithm that organizes high-dimensional vector embeddings into a multi-layered structure for logarithmic-time retrieval. In RAG pipelines, it balances high search throughput and recall at the cost of significantly higher RAM consumption compared to quantization-based indexing.
It is a specific indexing algorithm, not a vector database or an embedding model itself.
"An express elevator system in a skyscraper: the top floor has very few stops for fast traversal across the city, while the ground floor stops at every single door for precise location."
Conceptual Overview
Hierarchical Navigable Small World (HNSW) is a graph-based approximate nearest neighbor (ANN) search algorithm that organizes high-dimensional vector embeddings into a multi-layered structure for logarithmic-time retrieval. In RAG pipelines, it balances high search throughput and recall at the cost of significantly higher RAM consumption compared to quantization-based indexing.
Disambiguation
It is a specific indexing algorithm, not a vector database or an embedding model itself.
Visual Analog
An express elevator system in a skyscraper: the top floor has very few stops for fast traversal across the city, while the ground floor stops at every single door for precise location.