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Neon Postgres

Neon is a fully managed serverless PostgreSQL database. It separates storage and compute to offer features such as instant branching and automatic scaling.

With the pgvector extension, Neon provides a vector store that can be used with LangChain.js to store and query embeddings.

Setup​

Select a Neon project​

If you do not have a Neon account, sign up for one at Neon. After logging into the Neon Console, proceed to the Projects section and select an existing project or create a new one.

Your Neon project comes with a ready-to-use Postgres database named neondb that you can use to store embeddings. Navigate to the Connection Details section to find your database connection string. It should look similar to this:

postgres://alex:AbC123dEf@ep-cool-darkness-123456.us-east-2.aws.neon.tech/dbname?sslmode=require

Keep your connection string handy for later use.

Application code​

To work with Neon Postgres, you need to install the @neondatabase/serverless package which provides a JavaScript/TypeScript driver to connect to the database.

npm install @neondatabase/serverless
tip

See this section for general instructions on installing integration packages.

npm install @langchain/community @langchain/core

To initialize a NeonPostgres vectorstore, you need to provide your Neon database connection string. You can use the connection string we fetched above directly, or store it as an environment variable and use it in your code.

const vectorStore = await NeonPostgres.initialize(embeddings, {
  connectionString: NEON_POSTGRES_CONNECTION_STRING,
});

Optional​

You can put the vector store table in custom db schema by passing schemaName to the config options during initialization.

const vectorStore = await NeonPostgres.initialize(embeddings, {
  connectionString: NEON_POSTGRES_CONNECTION_STRING,
  schemaName: "mycustomschema",
});

## Usage

import CodeBlock from "@theme/CodeBlock";
import Example from "@examples/indexes/vector_stores/neon/example.ts";

<CodeBlock language="typescript">{Example}</CodeBlock>

## Related

- Vector store [conceptual guide](/docs/concepts/#vectorstores)
- Vector store [how-to guides](/docs/how_to/#vectorstores)

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