AzureAISearchBM25Retriever

Retrieve documents from an AzureAISearchDocumentStore using BM25 keyword search.

Key Features

• Keyword-based full-text retrieval from Azure AI Search.
• Configurable number of results with top_k.
• Supports metadata filtering to narrow down the search space.
• Supports advanced Azure AI Search query types, including simple, full, and semantic.
• Configurable filter policy (replace or merge) for runtime filters.

Configuration

1. Drag the AzureAISearchBM25Retriever component onto the canvas from the Component Library.
2. Click on the component to open the configuration panel.
3. On the General tab:
   • Configure the AzureAISearchDocumentStore with your Azure AI Search instance details.
   • Set top_k to control the maximum number of documents to retrieve.
4. Go to the Advanced tab to configure filter_policy and additional Azure AI Search query options.

Connections

AzureAISearchBM25Retriever receives the user query as a text string, typically from the Input component. It sends retrieved documents to downstream components such as PromptBuilder or a ranker.

Source Code

To check this component's source code, open bm25_retriever.py in the Haystack Core Integrations repository.

Usage Examples

Basic Configuration

  AzureAISearchBM25Retriever:
    type: haystack_integrations.components.retrievers.azure_ai_search.bm25_retriever.AzureAISearchBM25Retriever
    init_parameters:
      top_k: 10
      document_store:
        type: haystack_integrations.document_stores.azure_ai_search.document_store.AzureAISearchDocumentStore
        init_parameters:
          api_key:
            type: env_var
            env_vars:
            - AZURE_SEARCH_API_KEY
            strict: false
          azure_endpoint:
            type: env_var
            env_vars:
            - AZURE_SEARCH_SERVICE_ENDPOINT
            strict: false
          index_name: my-index

Parameters

Inputs

Parameter	Type	Description
query	str	The text query to search for.
filters	Optional[Dict[str, Any]]	Filters to apply to the search results.
top_k	Optional[int]	The maximum number of documents to return.

Outputs

Parameter	Type	Description
documents	List[Document]	The retrieved documents.

Init Parameters

These are the parameters you can configure in Pipeline Builder:

Parameter	Type	Default	Description
document_store	AzureAISearchDocumentStore		An instance of AzureAISearchDocumentStore.
filters	Optional[Dict[str, Any]]	None	Default filters applied when running the retriever.
top_k	int	10	The maximum number of documents to retrieve.
filter_policy	Union[str, FilterPolicy]	FilterPolicy.REPLACE	Policy for how runtime filters are applied relative to init-time filters.

Run Method Parameters

These are the parameters you can configure for the component's run() method. This means you can pass these parameters at query time through the API, in Playground, or when running a job. For details, see Modify Pipeline Parameters at Query Time.

Parameter	Type	Default	Description
query	str		The text query to search for.
filters	Optional[Dict[str, Any]]	None	Filters to apply at query time.
top_k	Optional[int]	None	Override the init-time top_k setting.

Related Information

• AzureAISearchEmbeddingRetriever
• Pipeline Components