How to connect PolyBase to Google Cloud Storage

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

Connect to Google Cloud Storage

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 Google Cloud Storage Sys is created automatically).

Authenticate with a User Account

You can connect without setting any connection properties for your user credentials. After setting InitiateOAuth to GETANDREFRESH, you are ready to connect.

When you connect, the Google Cloud Storage OAuth endpoint opens in your default browser. Log in and grant permissions, then the OAuth process completes

Authenticate with a Service Account

Service accounts have silent authentication, without user authentication in the browser. You can also use a service account to delegate enterprise-wide access scopes.

You need to create an OAuth application in this flow. See the Help documentation for more information. After setting the following connection properties, you are ready to connect:

• InitiateOAuth: Set this to GETANDREFRESH.
• OAuthJWTCertType: Set this to "PFXFILE".
• OAuthJWTCert: Set this to the path to the .p12 file you generated.
• OAuthJWTCertPassword: Set this to the password of the .p12 file.
• OAuthJWTCertSubject: Set this to "*" to pick the first certificate in the certificate store.
• OAuthJWTIssuer: In the service accounts section, click Manage Service Accounts and set this field to the email address displayed in the service account Id field.
• OAuthJWTSubject: Set this to your enterprise Id if your subject type is set to "enterprise" or your app user Id if your subject type is set to "user".
• ProjectId: Set this to the Id of the project you want to connect to.

The OAuth flow for a service account then completes.

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

Create an External Data Source for Google Cloud Storage 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 Google Cloud Storage data.

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

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

Create an External Data Source for Google Cloud Storage

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

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

For Google Cloud Storage, 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_googlecloudstorage_source
WITH ( 
  LOCATION = 'odbc://SERVER_URL',
  CONNECTION_OPTIONS = 'DSN=CData Google Cloud Storage Sys',
  -- PUSHDOWN = ON | OFF,
  CREDENTIAL = googlecloudstorage_creds
);

Create External Tables for Google Cloud Storage

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

CREATE EXTERNAL TABLE Buckets(
  Name [nvarchar](255) NULL,
  OwnerId [nvarchar](255) NULL,
  ...
) WITH ( 
  LOCATION='Buckets',
  DATA_SOURCE=cdata_googlecloudstorage_source
);

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