# OpenSearch Explain with Hybrid Radial Search

**URL:** <https://forum.opensearch.org/t/opensearch-explain-with-hybrid-radial-search/25375>\
**Category:** OpenSearch\
**Tags:** discuss\
**Created:** [June 30, 2025, 6:59am UTC](https://forum.opensearch.org/t/opensearch-explain-with-hybrid-radial-search/25375 "2025-06-30T06:59:41Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![OSvince](https://avatars.discourse-cdn.com/v4/letter/o/cdc98d/32.png) [@OSvince](https://forum.opensearch.org/u/OSvince)\
**Post date:** [June 30, 2025, 6:59am UTC](https://forum.opensearch.org/t/opensearch-explain-with-hybrid-radial-search/25375/1 "2025-06-30T06:59:41Z")

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**Versions** (relevant - OpenSearch/Dashboard/Server OS/Browser):

OpenSearch 2.19.2

**Describe the issue** :  
I’m exploring the `_explain` API in OpenSearch to improve the relevancy of my queries. I’m currently using a hybrid query that combines lexical and neural search, along with radial search using `min_score`.

However, when I check the explanation for the neural part, it always just says “within top k” in the description. I also tried isolating the neural part of the hybrid query to inspect it separately, but the explanation returns “no explanation.”

Is this a limitation of the `_explain` API—that it currently doesn’t provide detailed information for the neural component?

**Configuration** :  
L2 normalization  
Faiss engine

**Relevant Logs or Screenshots** :

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**Author:** ![pablo](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.opensearch.org/pablo/32/10363_2.png) [@pablo](https://forum.opensearch.org/u/pablo)\
**Post date:** [June 30, 2025, 9:24am UTC](https://forum.opensearch.org/t/opensearch-explain-with-hybrid-radial-search/25375/2 "2025-06-30T09:24:57Z")

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@OSvince Have you tested 3.0.0 or 3.1.0? There were improvements around the \_explain API.

> <https://github.com/opensearch-project/opensearch-build/blob/main/release-notes/opensearch-release-notes-3.0.0.md#opensearch-k-nn-1>

> <https://github.com/opensearch-project/k-NN/pull/2403>
>
> \### Description
> Add support for explain for Exact/ANN/Radial/Disk/Filtering k-n…n search. Score calculation explanation is currently added only for ANN search.
> Proposal for explain is given here: https://github.com/opensearch-project/k-NN/issues/875#issuecomment-2611349466
> 
> \### Related Issues
> Resolves #875
> 
> 
> \### Check List
> \- \[x\] New functionality includes testing.
> \- \[\] New functionality has been documented.
> \- \[\] API changes companion pull request \[created\](https://github.com/opensearch-project/opensearch-api-specification/blob/main/DEVELOPER\_GUIDE.md).
> \- \[x\] Commits are signed per the DCO using \`--signoff\`.
> \- \[x\] Public documentation issue/PR \[created\](https://github.com/opensearch-project/documentation-website/issues/new/choose).
> 
> By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
> For more information on following Developer Certificate of Origin and signing off your commits, please check \[here\](https://github.com/opensearch-project/k-NN/blob/main/CONTRIBUTING.md#developer-certificate-of-origin).