Qdrant 集成

使用 LangChain Python 集成 Qdrant 向量存储。

Qdrant (read: quadrant) is a vector similarity search engine. It provides a production-ready service with a convenient API to store, search, and manage vectors with additional payload and extended filtering support. It makes it useful for all sorts of neural network or semantic-based matching, faceted search, and other applications.

This documentation demonstrates how to use Qdrant with LangChain for dense (i.e., embedding-based), sparse (i.e., text search) and hybrid retrieval. The QdrantVectorStore class supports multiple retrieval modes via Qdrant’s new Query API. It requires you to run Qdrant v1.10.0 or above.

设置

There are various modes of how to run Qdrant, and depending on the chosen one, there will be some subtle differences. The options include:

• Local mode, no server required
• Docker deployments
• Qdrant Cloud

Please see the Qdrant installation instructions.

pip install -qU langchain-qdrant

凭证

There are no credentials needed to run the code in this notebook.

如果您希望获得一流的模型调用自动追踪功能，还可以通过取消注释以下代码来设置 LangSmith API 密钥：

os.environ["LANGSMITH_API_KEY"] = getpass.getpass("Enter your LangSmith API key: ")
os.environ["LANGSMITH_TRACING"] = "true"

初始化

Local mode

The Python client provides the option to run the code in local mode without running the Qdrant server. This is great for testing things out and debugging or storing just a small amount of vectors. The embeddings can be kept fully in-memory or persisted on-disk.

In-memory

For some testing scenarios and quick experiments, you may prefer to keep all the data in-memory only, so it gets removed when the client is destroyed - usually at the end of your script/notebook.

# | output: false
# | echo: false
from langchain_openai import OpenAIEmbeddings

embeddings = OpenAIEmbeddings(model="text-embedding-3-large")

from langchain_qdrant import QdrantVectorStore
from qdrant_client import QdrantClient
from qdrant_client.http.models import Distance, VectorParams

client = QdrantClient(":memory:")

client.create_collection(
    collection_name="demo_collection",
    vectors_config=VectorParams(size=3072, distance=Distance.COSINE),
)

vector_store = QdrantVectorStore(
    client=client,
    collection_name="demo_collection",
    embedding=embeddings,
)

On-disk storage

Local mode, without using the Qdrant server, may also store your vectors on-disk so they persist between runs.

client = QdrantClient(path="/tmp/langchain_qdrant")

client.create_collection(
    collection_name="demo_collection",
    vectors_config=VectorParams(size=3072, distance=Distance.COSINE),
)

vector_store = QdrantVectorStore(
    client=client,
    collection_name="demo_collection",
    embedding=embeddings,
)

On-premise server deployment

No matter if you choose to launch Qdrant locally with a Docker container or select a Kubernetes deployment with the official Helm chart, the way you’re going to connect to such an instance will be identical. You’ll need to provide a URL pointing to the service.

url = "<---qdrant url here --->"
docs = []  # put docs here
qdrant = QdrantVectorStore.from_documents(
    docs,
    embeddings,
    url=url,
    prefer_grpc=True,
    collection_name="my_documents",
)

Qdrant cloud

If you prefer not to keep yourself busy with managing the infrastructure, you can choose to set up a fully-managed Qdrant cluster on Qdrant Cloud. There is a free forever 1GB cluster included for trying out. The main difference with using a managed version of Qdrant is that you’ll need to provide an API key to secure your deployment from being accessed publicly. The value can also be set in a QDRANT_API_KEY environment variable.

url = "<---qdrant cloud cluster url here --->"
api_key = "<---api key here--->"
qdrant = QdrantVectorStore.from_documents(
    docs,
    embeddings,
    url=url,
    prefer_grpc=True,
    api_key=api_key,
    collection_name="my_documents",
)

Using an existing collection

To get an instance of langchain_qdrant.Qdrant without loading any new documents or texts, you can use the Qdrant.from_existing_collection() method.

qdrant = QdrantVectorStore.from_existing_collection(
    embedding=embeddings,
    collection_name="my_documents",
    url="http://localhost:6333",
)

管理向量存储

创建向量存储后，我们可以通过添加和删除不同的项目来与其交互。

向向量存储添加项目

我们可以使用 add_documents 函数向向量存储添加项目。

from uuid import uuid4

from langchain_core.documents import Document

document_1 = Document(
    page_content="I had chocolate chip pancakes and scrambled eggs for breakfast this morning.",
    metadata={"source": "tweet"},
)

document_2 = Document(
    page_content="The weather forecast for tomorrow is cloudy and overcast, with a high of 62 degrees Fahrenheit.",
    metadata={"source": "news"},
)

document_3 = Document(
    page_content="Building an exciting new project with LangChain - come check it out!",
    metadata={"source": "tweet"},
)

document_4 = Document(
    page_content="Robbers broke into the city bank and stole $1 million in cash.",
    metadata={"source": "news"},
)

document_5 = Document(
    page_content="Wow! That was an amazing movie. I can't wait to see it again.",
    metadata={"source": "tweet"},
)

document_6 = Document(
    page_content="Is the new iPhone worth the price? Read this review to find out.",
    metadata={"source": "website"},
)

document_7 = Document(
    page_content="The top 10 soccer players in the world right now.",
    metadata={"source": "website"},
)

document_8 = Document(
    page_content="LangGraph is the best framework for building stateful, agentic applications!",
    metadata={"source": "tweet"},
)

document_9 = Document(
    page_content="The stock market is down 500 points today due to fears of a recession.",
    metadata={"source": "news"},
)

document_10 = Document(
    page_content="I have a bad feeling I am going to get deleted :(",
    metadata={"source": "tweet"},
)

documents = [
    document_1,
    document_2,
    document_3,
    document_4,
    document_5,
    document_6,
    document_7,
    document_8,
    document_9,
    document_10,
]
uuids = [str(uuid4()) for _ in range(len(documents))]

vector_store.add_documents(documents=documents, ids=uuids)

从向量存储删除项目

vector_store.delete(ids=[uuids[-1]])

True

查询向量存储

Once your vector store has been created and the relevant documents have been added, you will most likely wish to query it during the running of your chain or agent.

直接查询

The simplest scenario for using the Qdrant vector store is to perform a similarity search. Under the hood, our query will be encoded into vector embeddings and used to find similar documents in a Qdrant collection.

results = vector_store.similarity_search(
    "LangChain provides abstractions to make working with LLMs easy", k=2
)
for res in results:
    print(f"* {res.page_content} [{res.metadata}]")

* Building an exciting new project with LangChain - come check it out! [{'source': 'tweet', '_id': 'd3202666-6f2b-4186-ac43-e35389de8166', '_collection_name': 'demo_collection'}]
* LangGraph is the best framework for building stateful, agentic applications! [{'source': 'tweet', '_id': '91ed6c56-fe53-49e2-8199-c3bb3c33c3eb', '_collection_name': 'demo_collection'}]

QdrantVectorStore supports 3 modes for similarity searches. They can be configured using the retrieval_mode parameter.

• Dense Vector Search (default)
• Sparse Vector Search
• Hybrid Search

Dense vector search

Dense vector search involves calculating similarity via vector-based embeddings. To search with only dense vectors:

• The retrieval_mode parameter should be set to RetrievalMode.DENSE. This is the default behavior.
• A dense embeddings value should be provided to the embedding parameter.

from langchain_qdrant import QdrantVectorStore, RetrievalMode
from qdrant_client import QdrantClient
from qdrant_client.http.models import Distance, VectorParams

# Create a Qdrant client for local storage
client = QdrantClient(path="/tmp/langchain_qdrant")

# Create a collection with dense vectors
client.create_collection(
    collection_name="my_documents",
    vectors_config=VectorParams(size=3072, distance=Distance.COSINE),
)

qdrant = QdrantVectorStore(
    client=client,
    collection_name="my_documents",
    embedding=embeddings,
    retrieval_mode=RetrievalMode.DENSE,
)

qdrant.add_documents(documents=documents, ids=uuids)

query = "How much money did the robbers steal?"
found_docs = qdrant.similarity_search(query)
found_docs

Sparse vector search

To search with only sparse vectors:

• The retrieval_mode parameter should be set to RetrievalMode.SPARSE.
• An implementation of the SparseEmbeddings interface using any sparse embeddings provider has to be provided as a value to the sparse_embedding parameter.

The langchain-qdrant package provides a FastEmbed based implementation out of the box.

To use it, install the FastEmbed package.

pip install -qU fastembed

from langchain_qdrant import FastEmbedSparse, QdrantVectorStore, RetrievalMode
from qdrant_client import QdrantClient, models
from qdrant_client.http.models import Distance, SparseVectorParams, VectorParams

sparse_embeddings = FastEmbedSparse(model_name="Qdrant/bm25")

# Create a Qdrant client for local storage
client = QdrantClient(path="/tmp/langchain_qdrant")

# Create a collection with sparse vectors
client.create_collection(
    collection_name="my_documents",
    vectors_config={"dense": VectorParams(size=3072, distance=Distance.COSINE)},
    sparse_vectors_config={
        "sparse": SparseVectorParams(index=models.SparseIndexParams(on_disk=False))
    },
)

qdrant = QdrantVectorStore(
    client=client,
    collection_name="my_documents",
    sparse_embedding=sparse_embeddings,
    retrieval_mode=RetrievalMode.SPARSE,
    sparse_vector_name="sparse",
)

qdrant.add_documents(documents=documents, ids=uuids)

query = "How much money did the robbers steal?"
found_docs = qdrant.similarity_search(query)
found_docs

Hybrid vector search

To perform a hybrid search using dense and sparse vectors with score fusion,

• The retrieval_mode parameter should be set to RetrievalMode.HYBRID.
• A dense embeddings value should be provided to the embedding parameter.
• An implementation of the SparseEmbeddings interface using any sparse embeddings provider has to be provided as a value to the sparse_embedding parameter.

Note that if you’ve added documents with the HYBRID mode, you can switch to any retrieval mode when searching, since both the dense and sparse vectors are available in the collection.

from langchain_qdrant import FastEmbedSparse, QdrantVectorStore, RetrievalMode
from qdrant_client import QdrantClient, models
from qdrant_client.http.models import Distance, SparseVectorParams, VectorParams

sparse_embeddings = FastEmbedSparse(model_name="Qdrant/bm25")

# Create a Qdrant client for local storage
client = QdrantClient(path="/tmp/langchain_qdrant")

# Create a collection with both dense and sparse vectors
client.create_collection(
    collection_name="my_documents",
    vectors_config={"dense": VectorParams(size=3072, distance=Distance.COSINE)},
    sparse_vectors_config={
        "sparse": SparseVectorParams(index=models.SparseIndexParams(on_disk=False))
    },
)

qdrant = QdrantVectorStore(
    client=client,
    collection_name="my_documents",
    embedding=embeddings,
    sparse_embedding=sparse_embeddings,
    retrieval_mode=RetrievalMode.HYBRID,
    vector_name="dense",
    sparse_vector_name="sparse",
)

qdrant.add_documents(documents=documents, ids=uuids)

query = "How much money did the robbers steal?"
found_docs = qdrant.similarity_search(query)
found_docs

如果您想执行相似度搜索并获取对应分数，可以运行：

results = vector_store.similarity_search_with_score(
    query="Will it be hot tomorrow", k=1
)
for doc, score in results:
    print(f"* [SIM={score:3f}] {doc.page_content} [{doc.metadata}]")

* [SIM=0.531834] The weather forecast for tomorrow is cloudy and overcast, with a high of 62 degrees. [{'source': 'news', '_id': '9e6ba50c-794f-4b88-94e5-411f15052a02', '_collection_name': 'demo_collection'}]

For a full list of all the search functions available for a QdrantVectorStore, read the API reference

元数据过滤

Qdrant has an extensive filtering system with rich type support. It is also possible to use the filters in LangChain, by passing an additional param to both the similarity_search_with_score and similarity_search methods.

from qdrant_client import models

results = vector_store.similarity_search(
    query="Who are the best soccer players in the world?",
    k=1,
    filter=models.Filter(
        should=[
            models.FieldCondition(
                key="page_content",
                match=models.MatchValue(
                    value="The top 10 soccer players in the world right now."
                ),
            ),
        ]
    ),
)
for doc in results:
    print(f"* {doc.page_content} [{doc.metadata}]")

* The top 10 soccer players in the world right now. [{'source': 'website', '_id': 'b0964ab5-5a14-47b4-a983-37fa5c5bd154', '_collection_name': 'demo_collection'}]

转换为检索器进行查询

您还可以将向量存储转换为检索器，以便在链中更方便地使用。

retriever = vector_store.as_retriever(search_type="mmr", search_kwargs={"k": 1})
retriever.invoke("Stealing from the bank is a crime")

[Document(metadata={'source': 'news', '_id': '50d8d6ee-69bf-4173-a6a2-b254e9928965', '_collection_name': 'demo_collection'}, page_content='Robbers broke into the city bank and stole $1 million in cash.')]

用于检索增强生成

有关如何将此向量存储用于检索增强生成 (RAG) 的指南，请参阅以下部分：

• Tutorials
• How-to: Question and answer with RAG
• Retrieval conceptual docs

Customizing qdrant

There are options to use an existing Qdrant collection within your LangChain application. In such cases, you may need to define how to map Qdrant point into the LangChain Document.

Named vectors

Qdrant supports multiple vectors per point by named vectors. If you work with a collection created externally or want to have the differently named vector used, you can configure it by providing its name.

from langchain_qdrant import RetrievalMode

QdrantVectorStore.from_documents(
    docs,
    embedding=embeddings,
    sparse_embedding=sparse_embeddings,
    location=":memory:",
    collection_name="my_documents_2",
    retrieval_mode=RetrievalMode.HYBRID,
    vector_name="custom_vector",
    sparse_vector_name="custom_sparse_vector",
)

Metadata

Qdrant stores your vector embeddings along with the optional JSON-like payload. Payloads are optional, but since LangChain assumes the embeddings are generated from the documents, we keep the context data, so you can extract the original texts as well.

By default, your document is going to be stored in the following payload structure:

{
    "page_content": "Lorem ipsum dolor sit amet",
    "metadata": {
        "foo": "bar"
    }
}

You can, however, decide to use different keys for the page content and metadata. That’s useful if you already have a collection that you’d like to reuse.

QdrantVectorStore.from_documents(
    docs,
    embeddings,
    location=":memory:",
    collection_name="my_documents_2",
    content_payload_key="my_page_content_key",
    metadata_payload_key="my_meta",
)

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API 参考

For detailed documentation of all QdrantVectorStore features and configurations head to the API reference

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