How to connect PolyBase to BigQuery

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 Google 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, and only for Standard SQL Server.

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

Connect to BigQuery

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 BigQuery Sys is created automatically).

Google uses the OAuth authentication standard. To access Google APIs on behalf of individual users, you can use the embedded credentials or you can register your own OAuth app.

OAuth also enables you to use a service account to connect on behalf of users in a Google Apps domain. To authenticate with a service account, you will need to register an application to obtain the OAuth JWT values.

In addition to the OAuth values, you will need to specify the DatasetId and ProjectId. See the "Getting Started" chapter of the help documentation for a guide to using OAuth.

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

Create an External Data Source for BigQuery 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 BigQuery data.

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

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

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:

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

For BigQuery, set SERVERNAME to the URL or address for your server (e.g. 'localhost' or '127.0.0.1' for local servers; the remote URL for remote servers). 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_googlebigquery_source
WITH ( 
  LOCATION = 'odbc://SERVER_URL',
  CONNECTION_OPTIONS = 'DSN=CData BigQuery Sys',
  -- PUSHDOWN = ON | OFF,
  CREDENTIAL = googlebigquery_creds
);

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 the CData ODBC Driver for Google BigQuery. 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 BigQuery 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_googlebigquery_source
);

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