RRF (Reciprocal Rank Fusion)

An algorithm for combining the rankings from multiple search systems (e.g. keyword search + vector search) into a single ordered list. Used in hybrid search to balance exact-match precision with semantic recall.

In depth

Reciprocal Rank Fusion is a search-engineering technique for merging the result lists from two or more independent retrieval methods. Each method assigns a rank to each candidate result; RRF turns those ranks into a single combined score using a formula that weights higher-ranked results more strongly while preventing any one method from dominating. In e-commerce search, RRF is the standard way to combine BM25 (keyword) and vector (semantic) results so a query like 'cheap warm winter jacket' returns products that match both the keyword 'jacket' and the underlying meaning 'insulated outerwear'. Emporiqa uses RRF as the default fusion strategy in its hybrid search pipeline. Neither pure keyword nor pure vector alone is robust enough for the variety of phrasing shoppers use.