QdrantHybridRetriever
A Retriever based both on dense and sparse embeddings, compatible with the Qdrant Document Store.
| Most common position in a pipeline | 1. After a Text Embedder and before a PromptBuilder in a RAG pipeline2. The last component in a hybrid search pipeline 3. After a Text Embedder and before an ExtractiveReader in an extractive QA pipeline |
| Mandatory init variables | "document_store": An instance of a QdrantDocumentStore |
| Mandatory run variables | “query_embedding”: A dense vector representing the query (a list of floats) “query_sparse_embedding”: A SparseEmbedding object containing a vectorial representation of the query |
| Output variables | “document”: A list of documents |
| API reference | Qdrant |
| GitHub link | https://github.com/deepset-ai/haystack-core-integrations/tree/main/integrations/qdrant |
Overview
The QdrantHybridRetriever is a Retriever based both on dense and sparse embeddings, compatible with the QdrantDocumentStore.
It compares the query and document’s dense and sparse embeddings and fetches the documents most relevant to the query from the QdrantDocumentStore, fusing the scores with Reciprocal Rank Fusion.
Hybrid Retrieval Pipeline
If you want additional customization for merging or fusing results, consider creating a hybrid retrieval pipeline with
DocumentJoiner.You can check out our hybrid retrieval pipeline tutorial for detailed steps.
When using the QdrantHybridRetriever, make sure it has the query and document with dense and sparse embeddings available. You can do so by:
- Adding a (dense) document Embedder and a sparse document Embedder to your indexing pipeline,
- Adding a (dense) text Embedder and a sparse text Embedder to your query pipeline.
In addition to query_embedding and query_sparse_embedding, the QdrantHybridRetriever accepts other optional parameters, including top_k (the maximum number of documents to retrieve) and filters to narrow down the search space.
Sparse Embedding Support
To use Sparse Embedding support, you need to initialize the
QdrantDocumentStorewithuse_sparse_embeddings=True, which isFalseby default.If you want to use Document Store or collection previously created with this feature disabled, you must migrate the existing data. You can do this by taking advantage of the
migrate_to_sparse_embeddings_supportutility function.
Installation
To start using Qdrant with Haystack, first install the package with:
pip install qdrant-haystack
Usage
On its own
from haystack_integrations.components.retrievers.qdrant import QdrantHybridRetriever
from haystack_integrations.document_stores.qdrant import QdrantDocumentStore
from haystack.dataclasses import Document, SparseEmbedding
document_store = QdrantDocumentStore(
":memory:",
use_sparse_embeddings=True,
recreate_index=True,
return_embedding=True,
wait_result_from_api=True,
)
doc = Document(content="test",
embedding=[0.5]*768,
sparse_embedding=SparseEmbedding(indices=[0, 3, 5], values=[0.1, 0.5, 0.12]))
document_store.write_documents([doc])
retriever = QdrantHybridRetriever(document_store=document_store)
embedding = [0.1]*768
sparse_embedding = SparseEmbedding(indices=[0, 1, 2, 3], values=[0.1, 0.8, 0.05, 0.33])
retriever.run(query_embedding=embedding, query_sparse_embedding=sparse_embedding)
In a pipeline
Currently, you can compute sparse embeddings using Fastembed Sparse Embedders.
First, install the package with:
pip install fastembed-haystack
In the example below, we are using Fastembed Embedders to compute dense embeddings as well.
from haystack import Document, Pipeline
from haystack.components.writers import DocumentWriter
from haystack_integrations.components.retrievers.qdrant import QdrantHybridRetriever
from haystack_integrations.document_stores.qdrant import QdrantDocumentStore
from haystack.document_stores.types import DuplicatePolicy
from haystack_integrations.components.embedders.fastembed import (
FastembedTextEmbedder,
FastembedDocumentEmbedder,
FastembedSparseTextEmbedder,
FastembedSparseDocumentEmbedder
)
document_store = QdrantDocumentStore(
":memory:",
recreate_index=True,
use_sparse_embeddings=True,
embedding_dim = 384
)
documents = [
Document(content="My name is Wolfgang and I live in Berlin"),
Document(content="I saw a black horse running"),
Document(content="Germany has many big cities"),
Document(content="fastembed is supported by and maintained by Qdrant."),
]
indexing = Pipeline()
indexing.add_component("sparse_doc_embedder", FastembedSparseDocumentEmbedder(model="prithvida/Splade_PP_en_v1"))
indexing.add_component("dense_doc_embedder", FastembedDocumentEmbedder(model="BAAI/bge-small-en-v1.5"))
indexing.add_component("writer", DocumentWriter(document_store=document_store, policy=DuplicatePolicy.OVERWRITE))
indexing.connect("sparse_doc_embedder", "dense_doc_embedder")
indexing.connect("dense_doc_embedder", "writer")
indexing_pipeline.run({"sparse_document_embedder": {"documents": documents}})
querying = Pipeline()
querying.add_component("sparse_text_embedder", FastembedSparseTextEmbedder(model="prithvida/Splade_PP_en_v1"))
querying.add_component("dense_text_embedder", FastembedTextEmbedder(
model="BAAI/bge-small-en-v1.5", prefix="Represent this sentence for searching relevant passages: ")
)
querying.add_component("retriever", QdrantHybridRetriever(document_store=document_store))
querying.connect("sparse_text_embedder.sparse_embedding", "retriever.query_sparse_embedding")
querying.connect("dense_text_embedder.embedding", "retriever.query_embedding")
question = "Who supports fastembed?"
results = query_mix.run(
{"dense_text_embedder": {"text": question},
"sparse_text_embedder": {"text": question}}
)
print(result["retriever"]["documents"][0])
# Document(id=...,
# content: 'fastembed is supported by and maintained by Qdrant.',
# score: 1.0)
Additional References
📓 Tutorial: Creating a Hybrid Retrieval Pipeline
🧑🍳 Cookbook: Sparse Embedding Retrieval with Qdrant and FastEmbed
Updated about 1 month ago