What is MMR (Maximal Marginal Relevance)?

Abbreviation: MMR

MMR is a re-ranking technique that balances relevance to the query against diversity among the selected results. osFoundry’s RAG pipelines include MMR as a configurable stage in osStudio.

Detail

Pure vector search often returns near-duplicate chunks — three slight variations of the same paragraph. MMR penalises similarity to already-selected results, so the final top-k spans more of the document space.

Useful when source documents have repetition or when you want broader coverage in the retrieved context. Tradeoff: slightly lower per-result relevance for more total information.

Related terms

reranking
retrieval
rag

Related features

custom-rag-pipeline