HNSW
Hierarchical Navigable Small World is an efficient graph-based algorithm for approximate nearest neighbor search in high-dimensional vector spaces.
Think of It Like This
Like an express elevator system where you take the fast elevator to the right zone before switching to local floors.
HNSW builds a multi-layered graph where the top layers have fewer, longer links for fast, coarse navigation, and bottom layers have dense links for precise searches. It is a foundational index structure powering modern vector databases due to its optimal balance of search speed and recall. It natively supports highly scalable semantic search applications.