---
title: Neo4j vector store
 | LlamaIndex OSS Documentation
---

If you’re opening this Notebook on colab, you will probably need to install LlamaIndex 🦙.

```
%pip install llama-index-vector-stores-neo4jvector
```

```
!pip install llama-index
```

```
import os
import openai


os.environ["OPENAI_API_KEY"] = "OPENAI_API_KEY"
openai.api_key = os.environ["OPENAI_API_KEY"]
```

## Initiate Neo4j vector wrapper

```
from llama_index.vector_stores.neo4jvector import Neo4jVectorStore


username = "neo4j"
password = "pleaseletmein"
url = "bolt://localhost:7687"
embed_dim = 1536


neo4j_vector = Neo4jVectorStore(username, password, url, embed_dim)
```

## Load documents, build the VectorStoreIndex

```
from llama_index.core import VectorStoreIndex, SimpleDirectoryReader
from IPython.display import Markdown, display
```

Download Data

```
!mkdir -p 'data/paul_graham/'
!wget 'https://raw.githubusercontent.com/run-llama/llama_index/main/docs/examples/data/paul_graham/paul_graham_essay.txt' -O 'data/paul_graham/paul_graham_essay.txt'
```

```
--2023-12-14 18:44:00--  https://raw.githubusercontent.com/run-llama/llama_index/main/docs/examples/data/paul_graham/paul_graham_essay.txt
Resolving raw.githubusercontent.com (raw.githubusercontent.com)... 185.199.111.133, 185.199.109.133, 185.199.110.133, ...
Connecting to raw.githubusercontent.com (raw.githubusercontent.com)|185.199.111.133|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 75042 (73K) [text/plain]
Saving to: ‘data/paul_graham/paul_graham_essay.txt’


data/paul_graham/pa 100%[===================>]  73,28K  --.-KB/s    in 0,03s


2023-12-14 18:44:00 (2,16 MB/s) - ‘data/paul_graham/paul_graham_essay.txt’ saved [75042/75042]
```

```
# load documents
documents = SimpleDirectoryReader("./data/paul_graham").load_data()
```

```
from llama_index.core import StorageContext


storage_context = StorageContext.from_defaults(vector_store=neo4j_vector)
index = VectorStoreIndex.from_documents(
    documents, storage_context=storage_context
)
```

```
query_engine = index.as_query_engine()
response = query_engine.query("What happened at interleaf?")
display(Markdown(f"<b>{response}</b>"))
```

**At Interleaf, they added a scripting language inspired by Emacs and made it a dialect of Lisp. They were looking for a Lisp hacker to write things in this scripting language. The author of the text worked at Interleaf and mentioned that their Lisp was the thinnest icing on a giant C cake. The author also mentioned that they didn’t know C and didn’t want to learn it, so they never understood most of the software at Interleaf. Additionally, the author admitted to being a bad employee and spending much of their time working on a separate project called On Lisp.**

## Hybrid search

Hybrid search uses a combination of keyword and vector search In order to use hybrid search, you need to set the `hybrid_search` to `True`

```
neo4j_vector_hybrid = Neo4jVectorStore(
    username, password, url, embed_dim, hybrid_search=True
)
```

```
storage_context = StorageContext.from_defaults(
    vector_store=neo4j_vector_hybrid
)
index = VectorStoreIndex.from_documents(
    documents, storage_context=storage_context
)
query_engine = index.as_query_engine()
response = query_engine.query("What happened at interleaf?")
display(Markdown(f"<b>{response}</b>"))
```

**At Interleaf, they added a scripting language inspired by Emacs and made it a dialect of Lisp. They were looking for a Lisp hacker to write things in this scripting language. The author of the essay worked at Interleaf but didn’t understand most of the software because he didn’t know C and didn’t want to learn it. He also mentioned that their Lisp was the thinnest icing on a giant C cake. The author admits to being a bad employee and spending much of his time working on a contract to publish On Lisp.**

## Load existing vector index

In order to connect to an existing vector index, you need to define the `index_name` and `text_node_property` parameters:

- index\_name: name of the existing vector index (default is `vector`)
- text\_node\_property: name of the property that containt the text value (default is `text`)

```
index_name = "existing_index"
text_node_property = "text"
existing_vector = Neo4jVectorStore(
    username,
    password,
    url,
    embed_dim,
    index_name=index_name,
    text_node_property=text_node_property,
)


loaded_index = VectorStoreIndex.from_vector_store(existing_vector)
```

## Customizing responses

You can customize the retrieved information from the knowledge graph using the `retrieval_query` parameter.

The retrieval query must return the following four columns:

- text:str - The text of the returned document
- score:str - similarity score
- id:str - node id
- metadata: Dict - dictionary with additional metadata (must contain `_node_type` and `_node_content` keys)

```
retrieval_query = (
    "RETURN 'Interleaf hired Tomaz' AS text, score, node.id AS id, "
    "{author: 'Tomaz', _node_type:node._node_type, _node_content:node._node_content} AS metadata"
)
neo4j_vector_retrieval = Neo4jVectorStore(
    username, password, url, embed_dim, retrieval_query=retrieval_query
)
```

```
loaded_index = VectorStoreIndex.from_vector_store(
    neo4j_vector_retrieval
).as_query_engine()
response = loaded_index.query("What happened at interleaf?")
display(Markdown(f"<b>{response}</b>"))
```

**Interleaf hired Tomaz.**