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Connect to as an External Data Source using PolyBase

Use the CData ODBC Driver for and PolyBase to create an external data source in SQL Server 2019 with access to live data.

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

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

Connect to

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 Sys is created automatically).

The primary method for performing basic authentication is to provide your login credentials, as follows:

  • User: Set this to your username.
  • Password: Set this to your password.

Optionally, if you are making use of a sandbox environment, set the following:

  • UseSandbox: Set this to true if you are authenticating with a sandbox account.

Authenticating Using Account Number and License Key

Alternatively, you can authenticate using your account number and license key. Connect to data using the following:

  • AccountId: Set this to your Account Id. The Account Id is listed in the upper right hand corner of the admin console.
  • LicenseKey: Set this to your Avalara Avatax license key. You can generate a license key by logging into Avalara Avatax as an account adminstrator and navigating to Settings -> Reset License Key.

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

Create an External Data Source for 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 data.

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

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

Create an External Data Source for

Execute the following SQL command to create an external data source for with PolyBase, using the DSN and credentials configured earlier.

For , set SERVERNAME to 'localhost' or '127.0.0.1' and leave PORT empty. PUSHDOWN is set to ON by default, meaning the ODBC Driver can leverage server-side processing for complex queries.

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

Create External Tables for

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

CREATE EXTERNAL TABLE Transactions(
  Id [nvarchar](255) NULL,
  TotalTax [nvarchar](255) NULL,
  ...
) WITH ( 
  LOCATION='Transactions',
  DATA_SOURCE=cdata_avalaraavatax_source
);

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