Hierarchical Navigable Small World Graph Indexing

via “hierarchical-navigable-small-world graph indexing”

A library for efficient similarity search and clustering of dense vectors.

Unique: Implements HNSW with Faiss-specific optimizations including batch insertion, configurable layer assignment strategies, and integration with other Faiss index types (e.g., HNSW+PQ for memory-efficient dynamic indexing). Provides ef parameter for query-time recall tuning without index reconstruction.

vs others: More memory-efficient than Hnswlib (the reference implementation) due to tighter C++ integration; supports composition with quantization (HNSW+PQ) whereas Hnswlib doesn't, enabling billion-scale dynamic indexing on CPU.

via “hierarchical and graph-based data indexing”