Hybrid Search Why Hybrid Dense vectors capture meaning but miss exact terms (product SKUs, error codes, proper nouns, code tokens). BM25 nails lexical matches but misses synonyms and paraphrases. Fusion consistently beats either alone on real-world corpora — typically +10-20% recall@10. Fusion Algorithms | Algorithm | Needs score calibration | Robust to list-size mismatch | Tunable | |---|---|---|---| | RRF (Reciprocal Rank Fusion) | No | Yes | k constant | | Weighted linear (alpha) | Yes (min-max normalize) | No | alpha | | CombSUM / CombMNZ | Yes | Partial | No | | Learned fusion (LTR) | Ye…