Improved Results With Vector Search in Knowledge Graphs Jennifer Reif jennifer.reif@neo4j.com @JMHReif github.com/JMHReif jmhreif.com linkedin.com/in/jmhreif Photo by Steve Johnson on Unsplash

What is Vector Search?

What is a vector? • Length • Direction • Components have meaning horizontal vertical

Vector Example - Shapes Length Width

Vector Example - Shapes Length Width

Vector arithmetic 1 a b 2 a b 3 a + b

Kings and Queens king − man + woman ≈ queen king man wom an 1 king man wom an 2 queen? 3

What are vector embeddings? Convert something to point in space • Same concepts, applied to data formats • 100s or 1000s of dimensions • Dimension = interesting feature/characteristic

Neighborhoods Cosine vs euclidean ● cosine ● direction / angle based vector point query nearest 4 ● Euclidean ● distance based

Vector index • Queries become expensive • Need to compare every vector to query • Indexes = speed • Jump right where you need (like index in a book) • Approximate nearest neighbor (k-ANN) • 20 closest vectors to this one

How to Add Vectors …to existing data

Data model

Data + Vectors How do I get vectors for existing data? • Generate some vector embeddings • Several models available • Store embedding as property on node

Examples OpenAI

APOC example WITH "" as apiKey MATCH (r:Review) WITH apiKey, r CALL { WITH apiKey, r CALL apoc.ml.openai.embedding([r.text], apiKey, {}) yield index, text, embedding CALL db.create.setNodeVectorProperty(r, 'embedding', embedding) RETURN r as review } RETURN review{.*};

Create and query vector index CALL db.index.vector.createNodeIndex('spring-ai-document-index', 'Review', 'embedding', 1536, 'cosine'); CALL db.index.vector.queryNodes('spring-ai-document-index', 10, $queryVector) YIELD node AS similarReviews, score MATCH (similarReviews)-[:WRITTEN_FOR]->(b:Book) RETURN b.title as title, avg(score) AS score ORDER BY score DESC LIMIT 10

Create and query vector index CALL db.index.vector.createNodeIndex( 'index-name', 'Label', 'propertyKey', 1536, 'cosine') CALL db.index.vector.queryNodes('index-name', 1000, $queryVector) valid: ● 'euclidean' ● 'cosine' OpenAI gen2 dimensions nearest 1000 to queryVector ● parameter ● alias ● property ● manually typed 😬 good luck Full documentation in Cypher manual https://neo4j.com/docs/cypher-manual/current/indexes-for-vector-search/ same name

Use LLM with Graph Vector Search

RAG • Retrieval: • Data retrieved from database • Augmented: • Augments response with facts • Generation: • Response in natural language Prompt + Relevant Information LLM API LLM
 Chat API User Database Search Prompt Response Relevant Results / Documents 2 3 1 Database

How much value can RAG add?

Explainable AI With RAG + LLM • How did the LLM get this answer? • Graphs: • Opportunity to log answers alongside context • Visualize conversations • Tools to analyze LLM performance

Example data model Agent Neo

Logging and Visualizing Conversations In same database as context Graph of an actual conversation between an Agent Neo user and the ChatGPT-4 LLM.
 Context Documents are labeled with their GDS Community.

Graph + Vector = Semantic Search Combine for more accurate results within a relevant context. Knowledge Graph Similarity Search Find similar documents. Vector Index Find related information. Graph Structure Pattern Matching

Demo Time!

Resources • Github repository (today’s code): github.com/JMHReif/springai-goodreads • GraphAcademy LLM courses: graphacademy.neo4j.com/categories/llms/ • Spring AI guide: neo4j.com/labs/genai-ecosystem/spring-ai • Docs for Spring AI: docs.spring.io/spring-ai/reference/api/vectordbs/neo4j.html • Docs for OpenAI embeddings: platform.openai.com/docs/guides/embeddings Jennifer Reif jennifer.reif@neo4j.com @JMHReif github.com/JMHReif jmhreif.com linkedin.com/in/jmhreif