---
title: Hybrid search
description: Hybrid search runs vector and keyword search in parallel and merges the results. It requires keyword search to be enabled. For an overview of search modes, refer to Search modes.
image: https://developers.cloudflare.com/dev-products-preview.png
---

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# Hybrid search

Hybrid search runs vector and keyword search in parallel and merges the results. It requires [keyword search](https://developers.cloudflare.com/ai-search/configuration/indexing/keyword-search/) to be enabled. For an overview of search modes, refer to [Search modes](https://developers.cloudflare.com/ai-search/concepts/search-modes/).

## Enable hybrid search

Set both `index_method.vector` and `index_method.keyword` to `true`:

TypeScript

```

const instance = await env.AI_SEARCH.create({

  id: "my-instance",

  index_method: {

    vector: true,

    keyword: true,

  },

  fusion_method: "rrf",

});


```

To disable hybrid search, set `index_method.keyword` to `false`. The keyword index is deleted.

For each search method, you can configure the following to adjust retrieval behavior:

* **Vector search**: Configure the [embedding model](https://developers.cloudflare.com/ai-search/configuration/models/).
* **Keyword search**: Configure the [tokenizer and match mode](https://developers.cloudflare.com/ai-search/configuration/indexing/keyword-search/).

## Fusion method

The `fusion_method` field controls how vector and keyword results are merged.

| Value | Default | Description                                                                                                               |
| ----- | ------- | ------------------------------------------------------------------------------------------------------------------------- |
| rrf   | Yes     | Reciprocal Rank Fusion. Scores results based on rank position across both search methods. Recommended for most use cases. |
| max   | No      | Takes the higher of the normalized vector and keyword scores. Use when one search method is consistently more relevant.   |

## Reranking

After fusion, you can optionally apply reranking to further reorder results by semantic relevance. Reranking uses a cross-encoder model that evaluates the query and each chunk together, which can improve precision beyond what fusion alone provides.

Reranking is disabled by default. Refer to [Reranking](https://developers.cloudflare.com/ai-search/configuration/retrieval/reranking/) to enable and configure it.

## Per-request overrides

Override search settings on individual requests using `ai_search_options.retrieval`.

| Field           | Type                             | Description                                                          |
| --------------- | -------------------------------- | -------------------------------------------------------------------- |
| retrieval\_type | "vector", "keyword", or "hybrid" | Force a specific search mode. Must be compatible with index\_method. |
| fusion\_method  | "rrf" or "max"                   | Override the fusion method.                                          |

TypeScript

```

const instance = env.AI_SEARCH.get("my-instance");


const results = await instance.search({

  messages: [{ role: "user", content: "What is Cloudflare?" }],

  ai_search_options: {

    retrieval: {

      retrieval_type: "hybrid",

      fusion_method: "rrf",

    },

  },

});


```

Explain Code

Note

Requesting a `retrieval_type` that is not compatible with the instance `index_method` returns an error.

## Scoring details

When hybrid search is active, each chunk includes a `scoring_details` object:

| Field            | Type   | Description                                 |
| ---------------- | ------ | ------------------------------------------- |
| vector\_score    | number | Vector similarity score (0 to 1).           |
| keyword\_score   | number | Raw BM25 keyword score.                     |
| vector\_rank     | number | Rank position in the vector result set.     |
| keyword\_rank    | number | Rank position in the keyword result set.    |
| fusion\_method   | string | Fusion method used (rrf or max).            |
| reranking\_score | number | Score from the reranking model, if enabled. |

## Limits

Instances with keyword search enabled support up to 500,000 files per instance on the Workers Paid tier, compared to 1,000,000 for vector-only instances. Refer to [Limits and pricing](https://developers.cloudflare.com/ai-search/platform/limits-pricing/) for the full list of limits.

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```