Neo4j

This section walks you through setting up Neo4jVectorStore to store document embeddings and perform similarity searches.

What is Neo4j?

Neo4j is an open-source NoSQL graph database. It is a fully transactional database (ACID) that stores data structured as graphs consisting of nodes, connected by relationships. Inspired by the structure of the real world, it allows for high query performance on complex data while remaining intuitive and simple for the developer.

What is Neo4j Vector Search?

Neo4j’s Vector Search got introduced in Neo4j 5.11 and was considered GA with the release of version 5.13. Embeddings can be stored on Node properties and can be queried with the db.index.vector.queryNodes() function. Those indexes are powered by Lucene using a Hierarchical Navigable Small World Graph (HNSW) to perform a k approximate nearest neighbors (k-ANN) query over the vector fields.

Prerequisites

OpenAI Account: Create an account at OpenAI Signup and generate the token at API Keys.
A running Neo4j (5.13+) instance
1. Docker image _neo4j:5.13
2. Neo4j Desktop
3. Neo4j Aura
4. Neo4j Server instance

Configuration

To connect to Neo4j and use the Neo4jVectorStore, you need to provide (e.g. via application.properties) configurations for your instance.

Additionally, you’ll need to provide your OpenAI API Key. Set it as an environment variable like so:

export SPRING_AI_OPENAI_API_KEY='Your_OpenAI_API_Key'

Repository

To acquire Spring AI artifacts, declare the Spring Snapshot repository:

<repository>
	<id>spring-snapshots</id>
	<name>Spring Snapshots</name>
	<url>https://repo.spring.io/snapshot</url>
	<releases>
		<enabled>false</enabled>
	</releases>
</repository>

Dependencies

Add these dependencies to your project:

OpenAI: Required for calculating embeddings.

<dependency>
	<groupId>org.springframework.experimental.ai</groupId>
	<artifactId>spring-ai-openai-spring-boot-starter</artifactId>
	<version>0.7.1-SNAPSHOT</version>
</dependency>

Neo4j Vector Store

<dependency>
	<groupId>org.springframework.experimental.ai</groupId>
	<artifactId>spring-ai-neo4j-store</artifactId>
	<version>0.7.1-SNAPSHOT</version>
</dependency>

Sample Code

To configure Neo4jVectorStore in your application, you can use the following setup:

Add to application.properties (using your Neo4j credentials):