Hybrid search without a second index
20 Jan 2026
Sparse indexes are the right tool for some lexical models. They are overhead when all you need is BM25-style weight on text you already keep in the payload.
1.4 scores those terms on the candidate set the dense walk already touches, then fuses. Exact-token queries stop losing to a vaguely similar paragraph.
If you truly need a learned sparse model with its own vocabulary, keep a named sparse vector. The engine still accepts it.