Why it matters

Hybrid outperforms pure vector or keyword. Standard modern RAG.

Advertisement

The architecture

Parallel: vector + BM25 search.

Fuse: RRF (reciprocal rank fusion).

Hybrid RAG structureVector searchsemanticBM25 searchlexicalRRF fusioncombined rankingRRF simple + effective; some use weighted linear combo
Hybrid RAG.
Advertisement

How it works end to end

Vector: dense embeddings.

BM25: sparse lexical.

RRF: sum 1/(k + rank) per doc.

Take top of fused list.