Hybrid Retrieval Systems in Production: Combining BM25, Dense Embeddings, and Reciprocal Rank Fusion
A deep architectural dive into lexical search limitations, vector space blindspots, and the mechanics of Reciprocal Rank Fusion.
Pure vector search frequently fails on exact keyword identifiers and domain jargon, while lexical BM25 misses semantic paraphrasing. This article breaks down the mathematical mechanics and implementation of Reciprocal Rank Fusion (RRF) for production RAG pipelines.