How to connect PolyBase to DB2

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 IBM DB2, you get access to your DB2 data directly alongside your SQL Server data. This article describes creating an external data source and external tables to grant access to live DB2 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 DB2 data using PolyBase due to optimized data processing built into the driver. When you issue complex SQL queries from SQL Server to DB2, the driver pushes down supported SQL operations, like filters and aggregations, directly to DB2 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 DB2 data, using a single query to pull data from distributed sources.

Connect to DB2

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 DB2 Sys is created automatically).

Set the following properties to connect to DB2:

• Server: Set this to the name of the server running DB2.
• Port: Set this to the port the DB2 server is listening on.
• Database: Set this to the name of the DB2 database.
• User: Set this to the username of a user allowed to access the database.
• Password: Set this to the password of a user allowed to access the database.

You will also need to install the corresponding DB2 driver:

• Windows: Install the IBM Data Server Provider for .NET.

  On Windows, installing the IBM Data Server Provider is sufficient, as the installation registers it in the machine.config.

• Java: Install the IBM Data Server Driver for JDBC.

  In the Java version, place the IBM Data Server Driver JAR in the www\WEB-INF\lib\ folder for this application.

Click "Test Connection" to ensure that the DSN is connected to DB2 properly. Navigate to the Tables tab to review the table definitions for DB2.

Create an External Data Source for DB2 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 DB2 data.

NOTE: IDENTITY and SECRET correspond with the User and Password properties for DB2.

CREATE DATABASE SCOPED CREDENTIAL db2_creds
WITH IDENTITY = 'db2_username', SECRET = 'db2_password';

Create an External Data Source for DB2

Execute a CREATE EXTERNAL DATA SOURCE SQL command to create an external data source for DB2 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 DB2. PUSHDOWN is set to ON by default, meaning the ODBC Driver can leverage server-side processing for complex queries.

CREATE EXTERNAL DATA SOURCE cdata_db2_source
WITH ( 
  LOCATION = 'odbc://SERVERNAME[:PORT]',
  CONNECTION_OPTIONS = 'DSN=CData DB2 Sys',
  -- PUSHDOWN = ON | OFF,
  CREDENTIAL = db2_creds
);

Create External Tables for DB2

After creating the external data source, use CREATE EXTERNAL TABLE statements to link to DB2 data from your SQL Server instance. The table column definitions must match those exposed by the CData ODBC Driver for IBM DB2. 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 DB2 Orders would look similar to the following:

CREATE EXTERNAL TABLE Orders(
  OrderName [nvarchar](255) NULL,
  Freight [nvarchar](255) NULL,
  ...
) WITH ( 
  LOCATION='Orders',
  DATA_SOURCE=cdata_db2_source
);

Having created external tables for DB2 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 DB2, freeing up local resources and computing power. Download a free, 30-day trial of the ODBC Driver for DB2 and start working with live DB2 data alongside your SQL Server data today.