nmslib/hnswlib
Hnswlib
hnswlib is a header-only C++ library and vector indexing engine designed for high-dimensional approximate nearest neighbor search. It organizes large collections of embeddings into a searchable graph structure to enable rapid proximity queries and distance calculations.
The system utilizes Hierarchical Navigable Small World graphs to achieve fast vector similarity search. It distinguishes itself by allowing the definition of custom distance metrics and similarity functions to adapt calculations to specific data requirements.
The engine covers the full indexing lifecycle, including incremental index construction and the management of data points through additions and element removal. Query capabilities include both approximate and exact nearest neighbor search, supplemented by boolean search filtering to exclude candidates based on element labels.
The library supports index persistence via binary file serialization and provides configurations for parallel execution to distribute query and indexing tasks across multiple CPU cores.
