Lesson 24← back to roadmap
ANN is mostly graph traversal in disguise. HNSW makes the disguise efficient.
Parameters that matter (docs/cpp/api-reference/config.md)
- max_connections (M) — outgoing edges per node per layer; default 16
- ef_construction — candidate-list size when inserting; default 200
- ef_search — candidate-list size at query time; default 50
Increase ef_search to trade latency for recall at query time without rebuilding. Increase ef_construction or max_connections only at build time — and only if your recall plateau is below target.