How to connect PolyBase to Lakebase

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 Lakebase, you get access to your Lakebase data directly alongside your SQL Server data. This article describes creating an external data source and external tables to grant access to live Lakebase data using T-SQL queries.

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

The CData ODBC drivers offer unmatched performance for interacting with live Lakebase data using PolyBase due to optimized data processing built into the driver. When you issue complex SQL queries from SQL Server to Lakebase, the driver pushes down supported SQL operations, like filters and aggregations, directly to Lakebase 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 Lakebase data, using a single query to pull data from distributed sources.

Connect to Lakebase

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 Lakebase Sys is created automatically).

• DatabricksInstance: The Databricks instance or server hostname, provided in the format instance-abcdef12-3456-7890-abcd-abcdef123456.database.cloud.databricks.com.
• Server: The host name or IP address of the server hosting the Lakebase database.
• Port (optional): The port of the server hosting the Lakebase database, set to 5432 by default.
• Database (optional): The database to connect to after authenticating to the Lakebase Server, set to the authenticating user's default database by default.

OAuth Client Authentication

To authenicate using OAuth client credentials, you need to configure an OAuth client in your service principal. In short, you need to do the following:

1. Create and configure a new service principal
2. Assign permissions to the service principal
3. Create an OAuth secret for the service principal

For more information, refer to the Setting Up OAuthClient Authentication section in the Help documentation.

OAuth PKCE Authentication

To authenticate using the OAuth code type with PKCE (Proof Key for Code Exchange), set the following properties:

• AuthScheme: OAuthPKCE.
• User: The authenticating user's user ID.

For more information, refer to the Help documentation.

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

Create an External Data Source for Lakebase 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 Lakebase data.

NOTE: Since Lakebase does not require a User or Password to authenticate, you may use whatever values you wish for IDENTITY and SECRET.

CREATE DATABASE SCOPED CREDENTIAL lakebase_creds
WITH IDENTITY = 'username', SECRET = 'password';

Create an External Data Source for Lakebase

Execute a CREATE EXTERNAL DATA SOURCE SQL command to create an external data source for Lakebase 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 Lakebase. PUSHDOWN is set to ON by default, meaning the ODBC Driver can leverage server-side processing for complex queries.

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

Create External Tables for Lakebase

After creating the external data source, use CREATE EXTERNAL TABLE statements to link to Lakebase data from your SQL Server instance. The table column definitions must match those exposed by the CData ODBC Driver for Lakebase. 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 Lakebase Orders would look similar to the following:

CREATE EXTERNAL TABLE Orders(
  ShipName [nvarchar](255) NULL,
  ShipCity [nvarchar](255) NULL,
  ...
) WITH ( 
  LOCATION='Orders',
  DATA_SOURCE=cdata_lakebase_source
);

Having created external tables for Lakebase 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 Lakebase, freeing up local resources and computing power. Download a free, 30-day trial of the ODBC Driver for Lakebase and start working with live Lakebase data alongside your SQL Server data today.