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URL: https://www.cdata.com/kb/tech/bigquery-cloud-polybase.rst

⇱ Connect to BigQuery Data as an External Data Source using PolyBase

Connect to BigQuery Data as an External Data Source using PolyBase

👁 Dibyendu Datta
Dibyendu Datta
Lead Technology Evangelist
Use CData Connect AI and PolyBase to create an external data source in SQL Swerver with access to live BigQuery 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 BigQuery, you get access to your BigQuery data directly alongside your SQL Server data. This article describes creating an external data source and external tables to grant access to live BigQuery data using T-SQL queries.

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

CData Connect AI provides a pure SQL Server interface for BigQuery, allowing you to query data from BigQuery without replicating the data to a natively supported database. Using optimized data processing out of the box, CData Connect AI pushes all supported SQL operations (filters, JOINs, etc.) directly to BigQuery, leveraging server-side processing to return the requested BigQuery data quickly.

About BigQuery Data Integration

CData simplifies access and integration of live Google BigQuery data. Our customers leverage CData connectivity to:

  • Simplify access to BigQuery with broad out-of-the-box support for authentication schemes, including OAuth, OAuth JWT, and GCP Instance.
  • Enhance data workflows with Bi-directional data access between BigQuery and other applications.
  • Perform key BigQuery actions like starting, retrieving, and canceling jobs; deleting tables; or insert job loads through SQL stored procedures.

Most CData customers are using Google BigQuery as their data warehouse and so use CData solutions to migrate business data from separate sources into BigQuery for comprehensive analytics. Other customers use our connectivity to analyze and report on their Google BigQuery data, with many customers using both solutions.

For more details on how CData enhances your Google BigQuery experience, check out our blog post: https://www.cdata.com/blog/what-is-bigquery


Getting Started


Configure BigQuery Connectivity for PolyBase

Connectivity to BigQuery from PolyBase is made possible through CData Connect AI. To work with BigQuery data from PolyBase, we start by creating and configuring a BigQuery connection.

  1. Log into Connect AI, click Sources, and then click Add Connection
    2. 👁 Adding a Connection
  2. Select "BigQuery" from the Add Connection panel
    3. 👁 Selecting a data source
  3. BigQuery uses OAuth to authenticate. Click "Sign in" to authenticate with BigQuery. 👁 Authenticating with OAuth (Salesforce is shown).
  4. Navigate to the Permissions tab in the Add BigQuery Connection page and update the User-based permissions. 👁 Updating permissions

Add a Personal Access Token

When connecting to Connect AI through the REST API, the OData API, or the Virtual SQL Server, a Personal Access Token (PAT) is used to authenticate the connection to Connect AI. It is best practice to create a separate PAT for each service to maintain granularity of access.

  1. Click on the Gear icon () at the top right of the Connect AI app to open the settings page.
  2. On the Settings page, go to the Access Tokens section and click Create PAT.
  3. Give the PAT a name and click Create. 👁 Creating a new PAT
  4. The personal access token is only visible at creation, so be sure to copy it and store it securely for future use.

With the connection configured and a PAT generated, you are ready to connect to BigQuery data from Polybase.

Create an External Data Source for BigQuery Data

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

Creating a Credential Database

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

NOTE: Set IDENTITY to your Connect AI username and set SECRET to your Personal Access Token.

CREATE DATABASE SCOPED CREDENTIAL ConnectCloudCredentials
WITH IDENTITY = 'yourusername', SECRET = 'yourPAT';

Create an External Data Source for BigQuery

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

CREATE EXTERNAL DATA SOURCE ConnectCloudInstance
WITH ( 
 LOCATION = 'sqlserver://tds.cdata.com:14333',
 PUSHDOWN = ON,
 CREDENTIAL = ConnectCloudCredentials
);

Create External Tables for BigQuery

After creating the external data source, use CREATE EXTERNAL TABLE statements to link to BigQuery data from your SQL Server instance. The table column definitions must match those exposed by CData Connect AI. You can use the Data Explorer in Connect AI to see the table definition.

👁 Table definition in the Data Explorer (Salesforce is shown)

Sample CREATE TABLE Statement

Execute a CREATE EXTERNAL TABLE SQL command to create the external table(s), using the collation and setting the LOCATION to three-part notation for the connection, catalog, and table. The statement to create an external table based on a BigQuery Orders would look similar to the following.

CREATE EXTERNAL TABLE Orders(
 OrderName COLLATE [nvarchar](255) NULL,
 Freight COLLATE [nvarchar](255) NULL,
 ...
) WITH ( 
 LOCATION='GoogleBigQuery1.GoogleBigQuery.Orders',
 DATA_SOURCE=ConnectCloudInstance
);

Having created external tables for BigQuery in your SQL Server instance, you are now able to query local and remote data simultaneously. To get live data access to hundreds of SaaS, Big Data, and NoSQL sources directly from your SQL Server database, try CData Connect AI today!