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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.

Setup

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.

Credentials

There are no credentials needed to run the code in this notebook. If you want to get best in-class automated tracing of your model calls you can also set your LangSmith API key by uncommenting below:

Initialization

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.

On-disk storage

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

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.

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.

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.

Manage vector store

Once you have created your vector store, we can interact with it by adding and deleting different items.

Add items to vector store

We can add items to our vector store by using the add_documents function.

Delete items from vector store

Query vector store

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.

Query directly

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.
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 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.
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.
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.
If you want to execute a similarity search and receive the corresponding scores you can run:
For a full list of all the search functions available for a QdrantVectorStore, read the API reference

Metadata filtering

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.

Query by turning into retriever

You can also transform the vector store into a retriever for easier usage in your chains.

Usage for retrieval-augmented generation

For guides on how to use this vector store for retrieval-augmented generation (RAG), see the following sections:

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.

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:
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.

API reference

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