---
title: Hybrid search
description: Combine vector and keyword search in AI Search for broader, more accurate retrieval results.
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",    },  },});
```

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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