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Overview

A vector store stores embedded data and performs similarity search.

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Interface

LangChain provides a unified interface for vector stores, allowing you to:
  • add_documents - Add documents to the store.
  • delete - Remove stored documents by ID.
  • similarity_search - Query for semantically similar documents.
This abstraction lets you switch between different implementations without altering your application logic.

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Initialization

To initialize a vector store, provide it with an embedding model: 
from langchain_core.vectorstores import InMemoryVectorStore
vector_store = InMemoryVectorStore(embedding=SomeEmbeddingModel())

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Adding documents

Add Document objects (holding page_content and optional metadata) like so: 
vector_store.add_documents(documents=[doc1, doc2], ids=["id1", "id2"])

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Deleting documents

Delete by specifying IDs: 
vector_store.delete(ids=["id1"])
Issue a semantic query using similarity_search, which returns the closest embedded documents: 
similar_docs = vector_store.similarity_search("your query here")
Many vector stores support parameters like:
  • k — number of results to return
  • filter — conditional filtering based on metadata

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Similarity metrics & indexing

Embedding similarity may be computed using:
  • Cosine similarity
  • Euclidean distance
  • Dot product
Efficient search often employs indexing methods such as HNSW (Hierarchical Navigable Small World), though specifics depend on the vector store.

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Metadata filtering

Filtering by metadata (e.g., source, date) can refine search results: 
vector_store.similarity_search(
  "query",
  k=3,
  filter={"source": "tweets"}
)

​
Top integrations

Select embedding model:
  • OpenAI
  • Azure
  • Google Gemini
  • Google Vertex
  • AWS
  • HuggingFace
  • Ollama
  • Cohere
  • Mistral AI
  • Nomic
  • NVIDIA
  • Voyage AI
  • IBM watsonx
  • Fake
  • xAI
  • Perplexity
  • DeepSeek
pip install -qU langchain-openai

import getpass
import os

if not os.environ.get("OPENAI_API_KEY"):
  os.environ["OPENAI_API_KEY"] = getpass.getpass("Enter API key for OpenAI: ")

from langchain_openai import OpenAIEmbeddings

embeddings = OpenAIEmbeddings(model="text-embedding-3-large")
Select vector store:
  • In-memory
  • AstraDB
  • Chroma
  • FAISS
  • Milvus
  • MongoDB
  • PGVector
  • PGVectorStore
  • Pinecone
  • Qdrant
pip install -qU langchain-core

from langchain_core.vectorstores import InMemoryVectorStore

vector_store = InMemoryVectorStore(embeddings)
VectorstoreDelete by IDFilteringSearch by VectorSearch with scoreAsyncPasses Standard TestsMulti TenancyIDs in add Documents
AstraDBVectorStore✅✅✅✅✅❌❌✅
Chroma✅✅✅✅✅✅✅✅
Clickhouse✅✅❌✅❌❌❌✅
CouchbaseSearchVectorStore✅✅✅✅✅❌✅✅
DatabricksVectorSearch✅✅✅✅✅❌❌✅
ElasticsearchStore✅✅✅✅✅❌❌✅
FAISS✅✅✅✅✅❌❌✅
InMemoryVectorStore✅✅❌✅✅❌❌✅
Milvus✅✅✅✅✅✅✅✅
MongoDBAtlasVectorSearch✅✅✅✅✅❌❌✅
openGauss✅✅✅✅❌✅❌✅
PGVector✅✅✅✅✅❌❌✅
PGVectorStore✅✅✅✅✅✅❌✅
PineconeVectorStore✅✅✅❌✅❌❌✅
QdrantVectorStore✅✅✅✅✅❌✅✅
Redis✅✅✅✅✅❌❌✅
Weaviate✅✅✅✅✅❌✅✅
SQLServer✅✅✅✅❌❌❌✅

​
All Vectorstores

Activeloop Deep Lake

Alibaba Cloud OpenSearch

AnalyticDB

Annoy

Apache Doris

ApertureDB

Astra DB Vector Store

Atlas

AwaDB

Azure Cosmos DB Mongo vCore

Azure Cosmos DB No SQL

Azure AI Search

Bagel

BagelDB

Baidu Cloud ElasticSearch VectorSearch

Baidu VectorDB

Apache Cassandra

Chroma

Clarifai

ClickHouse

Couchbase

DashVector

Databricks

IBM Db2

DingoDB

DocArray HnswSearch

DocArray InMemorySearch

Amazon Document DB

DuckDB

China Mobile ECloud ElasticSearch

Elasticsearch

Epsilla

Faiss

Faiss (Async)

FalkorDB

Gel

Google AlloyDB

Google BigQuery Vector Search

Google Cloud SQL for MySQL

Google Cloud SQL for PostgreSQL

Firestore

Google Memorystore for Redis

Google Spanner

Google Vertex AI Feature Store

Google Vertex AI Vector Search

Hippo

Hologres

Infinispan

Jaguar Vector Database

Kinetica

LanceDB

Lantern

Lindorm

LLMRails

ManticoreSearch

MariaDB

Marqo

Meilisearch

Amazon MemoryDB

Milvus

Momento Vector Index

MongoDB Atlas

MyScale

Neo4j Vector Index

NucliaDB

Oceanbase

openGauss

OpenSearch

Oracle AI Vector Search

Pathway

Postgres Embedding

PGVecto.rs

PGVector

PGVectorStore

Pinecone

Pinecone (sparse)

Qdrant

Relyt

Rockset

SAP HANA Cloud Vector Engine

ScaNN

SemaDB

SingleStore

scikit-learn

SQLiteVec

SQLite-VSS

SQLServer

StarRocks

Supabase

SurrealDB

Tablestore

Tair

Tencent Cloud VectorDB

ThirdAI NeuralDB

TiDB Vector

Tigris

TileDB

Timescale Vector

Typesense

Upstash Vector

USearch

Vald

VDMS

Vearch

Vectara

Vespa

viking DB

vlite

Weaviate

Xata

YDB

Yellowbrick

Zep

Zep Cloud

Zilliz

=======

Activeloop Deep Lake

Alibaba Cloud OpenSearch

AnalyticDB

Annoy

Apache Doris

ApertureDB

Astra DB Vector Store

Atlas

AwaDB

Azure Cosmos DB Mongo vCore

Azure Cosmos DB No SQL

Azure AI Search

Bagel

BagelDB

Baidu Cloud ElasticSearch VectorSearch

Baidu VectorDB

Apache Cassandra

Chroma

Clarifai

ClickHouse

Couchbase

DashVector

Databricks

IBM Db2

DingoDB

DocArray HnswSearch

DocArray InMemorySearch

Amazon Document DB

DuckDB

China Mobile ECloud ElasticSearch

Elasticsearch

Epsilla

Faiss

Faiss (Async)

FalkorDB

Gel

Google AlloyDB

Google BigQuery Vector Search

Google Cloud SQL for MySQL

Google Cloud SQL for PostgreSQL

Firestore

Google Memorystore for Redis

Google Spanner

Google Vertex AI Feature Store

Google Vertex AI Vector Search

Hippo

Hologres

Infinispan

Jaguar Vector Database

Kinetica

LanceDB

Lantern

Lindorm

LLMRails

ManticoreSearch

MariaDB

Marqo

Meilisearch

Amazon MemoryDB

Milvus

Momento Vector Index

MongoDB Atlas

MyScale

Neo4j Vector Index

NucliaDB

Oceanbase

openGauss

OpenSearch

Oracle AI Vector Search

Pathway

Postgres Embedding

PGVecto.rs

PGVector

PGVectorStore

Pinecone

Pinecone (sparse)

Qdrant

Redis

Relyt

Rockset

SAP HANA Cloud Vector Engine

ScaNN

SemaDB

SingleStore

scikit-learn

SQLiteVec

SQLite-VSS

SQLServer

StarRocks

Supabase

SurrealDB

Tablestore

Tair

Tencent Cloud VectorDB

ThirdAI NeuralDB

TiDB Vector

Tigris

TileDB

Timescale Vector

Typesense

Upstash Vector

USearch

Vald

VDMS

Vearch

Vectara

Vespa

viking DB

vlite

Weaviate

Xata

YDB

Yellowbrick

Zep

Zep Cloud

Zilliz