---
title: "AzureAISearchHybridRetriever"
id: azureaisearchhybridretriever
slug: "/azureaisearchhybridretriever"
description: "A Retriever based both on dense and sparse embeddings, compatible with the Azure AI Search Document Store."
---

# AzureAISearchHybridRetriever

A Retriever based both on dense and sparse embeddings, compatible with the Azure AI Search Document Store.

This Retriever combines embedding-based retrieval and BM25 text search search to find matching documents in the search index to get more relevant results.

|  |  |
| --- | --- |
| **Most common position in a pipeline** | 1. After a TextEmbedder and before a [`PromptBuilder`](../builders/promptbuilder.mdx) in a RAG pipeline 2. The last component in a hybrid search pipeline 3. After a TextEmbedder and before an [`ExtractiveReader`](../readers/extractivereader.mdx) in an extractive QA pipeline |
| **Mandatory init variables** | "document_store": An instance of [`AzureAISearchDocumentStore`](../../document-stores/azureaisearchdocumentstore.mdx)  |
| **Mandatory run variables** | "query": A string  <br /> <br />”query_embedding”: A list of floats |
| **Output variables** | “documents”: A list of documents (matching the query) |
| **API reference** | [Azure AI Search](/reference/integrations-azure_ai_search) |
| **GitHub link** | https://github.com/deepset-ai/haystack-core-integrations/tree/main/integrations/azure_ai_search |

## Overview

The `AzureAISearchHybridRetriever` combines vector retrieval and BM25 text search to fetch relevant documents from the `AzureAISearchDocumentStore`. It processes both textual (keyword) queries and query embeddings in a single request, executing all subqueries in parallel. The results are merged and reordered using [Reciprocal Rank Fusion (RRF)](https://learn.microsoft.com/en-us/azure/search/hybrid-search-ranking) to create a unified result set.

Besides the `query` and `query_embedding`, the `AzureAISearchHybridRetriever` accepts optional parameters such as `top_k` (the maximum number of documents to retrieve) and `filters` to refine the search. Additional keyword arguments can also be passed during initialization for further customization.

If your search index includes a [semantic configuration](https://learn.microsoft.com/en-us/azure/search/semantic-how-to-query-request), you can enable semantic ranking to apply it to the Retriever's results. For more details, refer to the [Azure AI documentation](https://learn.microsoft.com/en-us/azure/search/hybrid-search-how-to-query#semantic-hybrid-search).

For purely keyword-based retrieval, you can use `AzureAISearchBM25Retriever`, and for embedding-based retrieval, `AzureAISearchEmbeddingRetriever` is available.

## Usage

### Installation

This integration requires you to have an active Azure subscription with a deployed [Azure AI Search](https://azure.microsoft.com/en-us/products/ai-services/ai-search) service.

To start using Azure AI search with Haystack, install the package with:

```shell
pip install azure-ai-search-haystack
```

### On its own

This Retriever needs `AzureAISearchDocumentStore` and indexed documents to run.

```python
from haystack import Document
from haystack_integrations.components.retrievers.azure_ai_search import AzureAISearchHybridRetriever
from haystack_integrations.document_stores.azure_ai_search import AzureAISearchDocumentStore

document_store = AzureAISearchDocumentStore(index_name="haystack_docs")
documents = [Document(content="There are over 7,000 languages spoken around the world today."),
			       Document(content="Elephants have been observed to behave in a way that indicates a high level of self-awareness, such as recognizing themselves in mirrors."),
			       Document(content="In certain parts of the world, like the Maldives, Puerto Rico, and San Diego, you can witness the phenomenon of bioluminescent waves.")]
document_store.write_documents(documents=documents)

retriever = AzureAISearchHybridRetriever(document_store=document_store)
## fake embeddings to keep the example simple
retriever.run(query="How many languages are spoken around the world today?", query_embedding=[0.1]*384)
```

### In a RAG pipeline

The following example demonstrates using the `AzureAISearchHybridRetriever` in a pipeline. An indexing pipeline is responsible for indexing and storing documents with embeddings in the `AzureAISearchDocumentStore`, while the query pipeline uses hybrid retrieval to fetch relevant documents based on a given query.

```python
from haystack import Document, Pipeline
from haystack.components.embedders import SentenceTransformersDocumentEmbedder, SentenceTransformersTextEmbedder
from haystack.components.writers import DocumentWriter

from haystack_integrations.components.retrievers.azure_ai_search import AzureAISearchHybridRetriever
from haystack_integrations.document_stores.azure_ai_search import AzureAISearchDocumentStore

document_store = AzureAISearchDocumentStore(index_name="hybrid-retrieval-example")

model = "sentence-transformers/all-mpnet-base-v2"

documents = [
    Document(content="There are over 7,000 languages spoken around the world today."),
    Document(
        content="""Elephants have been observed to behave in a way that indicates a
         high level of self-awareness, such as recognizing themselves in mirrors."""
    ),
    Document(
        content="""In certain parts of the world, like the Maldives, Puerto Rico, and
          San Diego, you can witness the phenomenon of bioluminescent waves."""
    ),
]

document_embedder = SentenceTransformersDocumentEmbedder(model=model)
document_embedder.warm_up()

## Indexing Pipeline
indexing_pipeline = Pipeline()
indexing_pipeline.add_component(instance=document_embedder, name="doc_embedder")
indexing_pipeline.add_component(instance=DocumentWriter(document_store=document_store), name="doc_writer")
indexing_pipeline.connect("doc_embedder", "doc_writer")

indexing_pipeline.run({"doc_embedder": {"documents": documents}})

## Query Pipeline
query_pipeline = Pipeline()
query_pipeline.add_component("text_embedder", SentenceTransformersTextEmbedder(model=model))
query_pipeline.add_component("retriever", AzureAISearchHybridRetriever(document_store=document_store))
query_pipeline.connect("text_embedder.embedding", "retriever.query_embedding")

query = "How many languages are there?"

result = query_pipeline.run({"text_embedder": {"text": query}, "retriever": {"query": query}})

print(result["retriever"]["documents"][0])

```
