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Jev as an Elasticsearch Search Reranker

Elastic's Dustin Coates scores Elasticsearch hybrid search results with Jev and reranks them with a small Python policy, lifting nDCG@10 from 0.9351 to 0.9565 and Exact MRR from 0.9201 to 0.9616 across 250 Amazon Shopping Queries.
Format
Article
Reading time
2 min
Published by
Community
Author
Dustin Coates (Elastic)
Last verified
Oct 2026

Highlights

  • The best Jev policy lifted nDCG@10 from 0.9351 to 0.9565 on 250 US English queries from Amazon's Shopping Queries Dataset.
  • The same run improved Exact MRR from 0.9201 to 0.9616, closing roughly a quarter of the gap to perfect ranking.
  • The benchmark paired jev-1.13.0 with 4,754 labeled query/product pairs and compared BM25, hybrid search, and jina-reranker-v3.
  • Elasticsearch retrieved up to 40 candidates with an RRF retriever mixing multi_match and semantic_text search; Jev judged each pair.
  • The Choice question sorted pairs into exact, substitute, complement, and irrelevant; application code turned the scores into the final order.

Watch out

Published by Elastic with Jev as the only reranker under test on a single dataset of 250 queries and 4,754 pairs, so the gains are specific to that setup; no licence is stated for the companion notebook. The 70–500 ms latency and $0.042 per million input tokens are TypeSafe claims repeated by the article.

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YouTube: Jev in the reranking step of a RAG pipeline: why cosine similarity fails and how a steerable reranker compares. A Colab notebook comes with it.

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