How to connect PolyBase to Neo4J

PolyBase for SQL Server allows you to query external data by using the same Transact-SQL syntax used to query a database table. When paired with the CData ODBC Driver for Neo4J, you get access to your Neo4J data directly alongside your SQL Server data. This article describes creating an external data source and external tables to grant access to live Neo4J data using T-SQL queries.

NOTE: PolyBase is only available on SQL Server 19 and above, and only for Standard SQL Server.

The CData ODBC drivers offer unmatched performance for interacting with live Neo4J data using PolyBase due to optimized data processing built into the driver. When you issue complex SQL queries from SQL Server to Neo4J, the driver pushes down supported SQL operations, like filters and aggregations, directly to Neo4J and utilizes the embedded SQL engine to process unsupported operations (often SQL functions and JOIN operations) client-side. And with PolyBase, you can also join SQL Server data with Neo4J data, using a single query to pull data from distributed sources.

Connect to Neo4J

If you have not already, first specify connection properties in an ODBC DSN (data source name). This is the last step of the driver installation. You can use the Microsoft ODBC Data Source Administrator to create and configure ODBC DSNs. To create an external data source in SQL Server using PolyBase, configure a System DSN (CData Neo4J Sys is created automatically).

To connect to Neo4j, set the following connection properties:

• Server: The server hosting the Neo4j instance.
• Port: The port on which the Neo4j service is running. The provider connects to port 7474 by default.
• User: The username of the user using the Neo4j instance.
• Password: The password of the user using the Neo4j instance.

Click "Test Connection" to ensure that the DSN is connected to Neo4J properly. Navigate to the Tables tab to review the table definitions for Neo4J.

Create an External Data Source for Neo4J Data

After configuring the connection, you need to create a master encryption key and a credential database for the external data source.

Creating a Master Encryption Key

Execute the following SQL command to create a new master key, 'ENCRYPTION,' to encrypt the credentials for the external data source.

CREATE MASTER KEY ENCRYPTION BY PASSWORD = 'password';

Creating a Credential Database

Execute the following SQL command to create credentials for the external data source connected to Neo4J data.

NOTE: IDENTITY and SECRET correspond with the User and Password properties for Neo4J.

CREATE DATABASE SCOPED CREDENTIAL neo4j_creds
WITH IDENTITY = 'neo4j_username', SECRET = 'neo4j_password';

Create an External Data Source for Neo4J

Execute a CREATE EXTERNAL DATA SOURCE SQL command to create an external data source for Neo4J with PolyBase:

• Set the LOCATION parameter , using the DSN and credentials configured earlier.

NOTE: SERVERNAME and PORT corresponds to the Server and Port connection properties for Neo4J. PUSHDOWN is set to ON by default, meaning the ODBC Driver can leverage server-side processing for complex queries.

CREATE EXTERNAL DATA SOURCE cdata_neo4j_source
WITH ( 
  LOCATION = 'odbc://SERVERNAME[:PORT]',
  CONNECTION_OPTIONS = 'DSN=CData Neo4J Sys',
  -- PUSHDOWN = ON | OFF,
  CREDENTIAL = neo4j_creds
);

Create External Tables for Neo4J

After creating the external data source, use CREATE EXTERNAL TABLE statements to link to Neo4J data from your SQL Server instance. The table column definitions must match those exposed by the CData ODBC Driver for Neo4J. You can refer to the Tables tab of the DSN Configuration Wizard to see the table definition.

Sample CREATE TABLE Statement

The statement to create an external table based on a Neo4J ProductCategory would look similar to the following:

CREATE EXTERNAL TABLE ProductCategory(
  CategoryId [nvarchar](255) NULL,
  CategoryName [nvarchar](255) NULL,
  ...
) WITH ( 
  LOCATION='ProductCategory',
  DATA_SOURCE=cdata_neo4j_source
);

Having created external tables for Neo4J in your SQL Server instance, you are now able to query local and remote data simultaneously. Thanks to built-in query processing in the CData ODBC Driver, you know that as much query processing as possible is being pushed to Neo4J, freeing up local resources and computing power. Download a free, 30-day trial of the ODBC Driver for Neo4J and start working with live Neo4J data alongside your SQL Server data today.