AstraEmbeddingRetriever

Retrieve documents from an AstraDocumentStore using vector similarity search. Use this component in query pipelines to find semantically similar documents based on dense embeddings stored in DataStax Astra DB.

Embedding Models in Query Pipelines and Indexes

The embedding model you use to embed documents in your indexing pipeline must be the same as the embedding model you use to embed the query in your query pipeline.

This means the embedders for your indexing and query pipelines must match. For example, if you use CohereDocumentEmbedder to embed your documents, you should use CohereTextEmbedder with the same model to embed your queries.

Key Features

• Performs vector similarity search against documents stored in Astra DB.
• Supports cosine, dot product, and Euclidean similarity functions defined on the document store.
• Configurable filter policy to merge or replace filters at query time.
• Supports async execution via run_async.

Configuration

Add Workspace-Level Integration

1. Click your profile icon and choose Settings.
2. Go to Workspace>Integrations.
3. Find the provider you want to connect and click Connect next to them.
4. Enter the API key and any other required details.
5. Click Connect. You can use this integration in pipelines and indexes in the current workspace.

Add Organization-Level Integration

1. Click your profile icon and choose Settings.
2. Go to Organization>Integrations.
3. Find the provider you want to connect and click Connect next to them.
4. Enter the API key and any other required details.
5. Click Connect. You can use this integration in pipelines and indexes in all workspaces in the current organization.

1. First, configure an AstraDocumentStore in your pipeline.
2. Drag the AstraEmbeddingRetriever component onto the canvas from the Component Library.
3. Connect an embedder component to provide query_embedding as input.
4. Connect the retriever output to downstream components such as PromptBuilder.

Connections

AstraEmbeddingRetriever receives a query_embedding (list of floats) from a text embedder such as SentenceTransformersTextEmbedder. It outputs a list of Document objects you can connect to PromptBuilder or other downstream components.

Source Code

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

Usage Examples

Basic Configuration

  AstraEmbeddingRetriever:
    type: haystack_integrations.components.retrievers.astra.retriever.AstraEmbeddingRetriever
    init_parameters:
      document_store: AstraDocumentStore
      top_k: 5

Using the Component in a Pipeline

# haystack-pipeline
components:
  text_embedder:
    type: haystack.components.embedders.sentence_transformers_text_embedder.SentenceTransformersTextEmbedder
    init_parameters:
      model: sentence-transformers/all-MiniLM-L6-v2

  document_store:
    type: haystack_integrations.document_stores.astra.document_store.AstraDocumentStore
    init_parameters:
      api_endpoint:
        type: env_var
        env_vars:
        - ASTRA_DB_API_ENDPOINT
        strict: true
      token:
        type: env_var
        env_vars:
        - ASTRA_DB_APPLICATION_TOKEN
        strict: true
      collection_name: haystack_docs
      embedding_dimension: 384

  retriever:
    type: haystack_integrations.components.retrievers.astra.retriever.AstraEmbeddingRetriever
    init_parameters:
      document_store: document_store
      top_k: 5

connections:
- sender: text_embedder.embedding
  receiver: retriever.query_embedding

inputs:
  query:
  - text_embedder.text

outputs:
  documents: retriever.documents

Parameters

Inputs

Parameter	Type	Description
query_embedding	List[float]	The query embedding vector to search for similar documents.
filters	Optional[Dict[str, Any]]	Filters to apply when retrieving documents.
top_k	Optional[int]	The maximum number of documents to retrieve. Overrides the init-time value.

Outputs

Parameter	Type	Description
documents	List[Document]	A list of the most similar documents from the document store.

Init Parameters

These are the parameters you can configure in Pipeline Builder:

Parameter	Type	Default	Description
document_store	AstraDocumentStore		The Astra document store to retrieve documents from.
filters	Optional[Dict[str, Any]]	None	Default filters to apply when retrieving documents.
top_k	int	10	The maximum number of documents to retrieve.
filter_policy	FilterPolicy	FilterPolicy.REPLACE	How to handle filters passed at query time. REPLACE replaces init-time filters; MERGE combines them.

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_embedding	List[float]		The embedding vector to search with.
filters	Optional[Dict[str, Any]]	None	Runtime filters to apply.
top_k	Optional[int]	None	Maximum number of documents to retrieve. Overrides the init-time value.

Related Information

• AstraDocumentStore
• Pipeline Components