HNSW

Hierarchical Navigable Small World graphs are the default general-purpose ANN index.

When to use

• Medium-to-large collections where approximate nearest neighbor is acceptable
• Low-latency online query with tunable recall via ef_search

ZVec.NET mapping

Concern	Type / API
Build params	ZVecHnswIndexParam (M, EfConstruction, quantization, EnableRotate, …)
Query params	ZVecHnswQueryParams (EfSearch, radius, linear/refiner options)
Typed attribute	[ZVecVector(dim, M = …, EfConstruction = …)]

Pitfalls

• Higher M / EfConstruction improves recall and increases memory/build time
• Prefer includeVector: false when result embeddings are unused

Upstream

• zvec.org — index configuration and tuning
• First-party math: Theory: HNSW