# Using retrievers in the open source version

**URL:** <https://discuss.elastic.co/t/using-retrievers-in-the-open-source-version/374706>\
**Category:** Elasticsearch\
**Tags:** vector-search\
**Created:** [February 18, 2025, 8:10pm UTC](https://discuss.elastic.co/t/using-retrievers-in-the-open-source-version/374706 "2025-02-18T20:10:47Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Saleh\_AbuAli](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/saleh_abuali/32/141444_2.png) [@Saleh\_AbuAli](https://discuss.elastic.co/u/Saleh_AbuAli)\
**Post date:** [February 18, 2025, 8:10pm UTC](https://discuss.elastic.co/t/using-retrievers-in-the-open-source-version/374706/1 "2025-02-18T20:10:47Z")

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Hi, I’m looking to implement a hybrid search combining kNN and BM25. Is it possible to use retrievers in the open-source version of Elasticsearch to perform this in a single search query instead of using multi-search?

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**Author:** ![dadoonet](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/dadoonet/32/137187_2.png) [@dadoonet](https://discuss.elastic.co/u/dadoonet)\
**Post date:** [February 18, 2025, 8:49pm UTC](https://discuss.elastic.co/t/using-retrievers-in-the-open-source-version/374706/2 "2025-02-18T20:49:15Z")

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I already answered at [Implementing Hybrid Search with k-NN and BM25 in Elasticsearch Open Source](https://discuss.elastic.co/t/implementing-hybrid-search-with-k-nn-and-bm25-in-elasticsearch-open-source/374680)

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**Author:** ![Saleh\_AbuAli](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/saleh_abuali/32/141444_2.png) [@Saleh\_AbuAli](https://discuss.elastic.co/u/Saleh_AbuAli)\
**Post date:** [February 18, 2025, 9:13pm UTC](https://discuss.elastic.co/t/using-retrievers-in-the-open-source-version/374706/3 "2025-02-18T21:13:37Z")

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Thanks @dadoonet I was thinking we might be able to use different retrievers that available in the open source version, instead of RRF, to combine results from KNN and BM25.

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**Author:** ![dadoonet](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/dadoonet/32/137187_2.png) [@dadoonet](https://discuss.elastic.co/u/dadoonet)\
**Post date:** [February 18, 2025, 9:26pm UTC](https://discuss.elastic.co/t/using-retrievers-in-the-open-source-version/374706/4 "2025-02-18T21:26:03Z")

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I think we can continue the discussion in the other thread as it's related.