How to connect PolyBase to Teradata

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 Teradata, you get access to your Teradata data directly alongside your SQL Server data. This article describes creating an external data source and external tables to grant access to live Teradata 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 Teradata data using PolyBase due to optimized data processing built into the driver. When you issue complex SQL queries from SQL Server to Teradata, the driver pushes down supported SQL operations, like filters and aggregations, directly to Teradata 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 Teradata data, using a single query to pull data from distributed sources.

Connect to Teradata

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 Teradata Sys is created automatically).

To connect to Teradata, provide authentication information and specify the database server name.

• User: Set this to the username of a Teradata user.
• Password: Set this to the password of the Teradata user.
• DataSource: Specify the Teradata server name, DBC Name, or TDPID.
• Port: Specify the port the server is running on.
• Database: Specify the database name. If not specified, the default database is used.

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

Create an External Data Source for Teradata 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 Teradata data.

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

CREATE DATABASE SCOPED CREDENTIAL teradata_creds
WITH IDENTITY = 'teradata_username', SECRET = 'teradata_password';

Create an External Data Source for Teradata

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

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

PUSHDOWN is set to ON by default, meaning the ODBC Driver can leverage server-side processing for complex queries.

CREATE EXTERNAL DATA SOURCE cdata_teradata_source
WITH ( 
  LOCATION = 'odbc://SERVER_URL',
  CONNECTION_OPTIONS = 'DSN=CData Teradata Sys',
  -- PUSHDOWN = ON | OFF,
  CREDENTIAL = teradata_creds
);

Create External Tables for Teradata

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

CREATE EXTERNAL TABLE NorthwindProducts(
  ProductId [nvarchar](255) NULL,
  ProductName [nvarchar](255) NULL,
  ...
) WITH ( 
  LOCATION='NorthwindProducts',
  DATA_SOURCE=cdata_teradata_source
);

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