Connect to Azure Data Lake Storage Data as a SQL Server Linked Server

SQL Server Linked Servers enable the SQL Server Database Engine to read data from remote data sources and execute commands against the remote database servers outside of the instance of SQL Server. Typically, linked servers are configured to enable the execution of a T-SQL statement that includes tables in another instance of SQL Server, or another database product such as Oracle. When paired with CData Connect Cloud, linked servers provides instant access to Azure Data Lake Storage data from your SQL Server database. This article demonstrates how to connect to Azure Data Lake Storage using Connect Cloud and query Azure Data Lake Storage data in SQL Server Management Studio (SSMS).

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

Configure Azure Data Lake Storage Connectivity for SQL Server

Connectivity to Azure Data Lake Storage from SQL Linked Servers is made possible through CData Connect Cloud. To work with Azure Data Lake Storage data from SQL Linked Servers, we start by creating and configuring a Azure Data Lake Storage connection.

1. Log into Connect Cloud, click Connections and click Add Connection
2. Select "Azure Data Lake Storage" from the Add Connection panel
3. Enter the necessary authentication properties to connect to Azure Data Lake Storage.

   Authenticating to a Gen 1 DataLakeStore Account

   Gen 1 uses OAuth 2.0 in Azure AD for authentication.

   For this, an Active Directory web application is required. You can create one as follows:

   1. Sign in to your Azure Account through the .
   2. Select "Azure Active Directory".
   3. Select "App registrations".
   4. Select "New application registration".
   5. Provide a name and URL for the application. Select Web app for the type of application you want to create.
   6. Select "Required permissions" and change the required permissions for this app. At a minimum, "Azure Data Lake" and "Windows Azure Service Management API" are required.
   7. Select "Key" and generate a new key. Add a description, a duration, and take note of the generated key. You won't be able to see it again.

   To authenticate against a Gen 1 DataLakeStore account, the following properties are required:

   • Schema: Set this to ADLSGen1.
   • Account: Set this to the name of the account.
   • OAuthClientId: Set this to the application Id of the app you created.
   • OAuthClientSecret: Set this to the key generated for the app you created.
   • TenantId: Set this to the tenant Id. See the property for more information on how to acquire this.
   • Directory: Set this to the path which will be used to store the replicated file. If not specified, the root directory will be used.

   Authenticating to a Gen 2 DataLakeStore Account

   To authenticate against a Gen 2 DataLakeStore account, the following properties are required:

   • Schema: Set this to ADLSGen2.
   • Account: Set this to the name of the account.
   • FileSystem: Set this to the file system which will be used for this account.
   • AccessKey: Set this to the access key which will be used to authenticate the calls to the API. See the property for more information on how to acquire this.
   • Directory: Set this to the path which will be used to store the replicated file. If not specified, the root directory will be used.
4. Click Create & Test
5. Navigate to the Permissions tab in the Add Azure Data Lake Storage Connection page and update the User-based permissions.

Add a Personal Access Token

If you are connecting from a service, application, platform, or framework that does not support OAuth authentication, you can create a Personal Access Token (PAT) to use for authentication. Best practices would dictate that you create a separate PAT for each service, to maintain granularity of access.

1. Click on your username at the top right of the Connect Cloud app and click User Profile.
2. On the User Profile page, scroll down to the Personal Access Tokens section and click Create PAT.
3. Give your PAT a name and click Create.
4. The personal access token is only visible at creation, so be sure to copy it and store it securely for future use.

Connect to Azure Data Lake Storage from SQL Server using Connect Cloud

To establish a connection from SQL Server Linked Server to the CData Connect Cloud Virtual SQL Server API, follow these steps.

1. Open Microsoft SQL Server Management Studio.
2. In the Object Explorer pane, open Server Objects, right-click Linked Servers, and select New Linked Server.
3. The New Linked Server dialogue opens. On the General page, enter the following information:
   • Enter a name for the server in the Linked server field.
   • Select the radio button Other data source and select SQL Server Native Client 11.0 as the provider.
   • In the Data source field, enter tds.cdata.com,14333
   • In the Catalog field, enter enter the Connection Name of the CData Connect Cloud data source you want to connect to (for example, ADLS1).
4. Select the Security page. At the bottom, select the radio button labeled Be made using this security context and enter the following information:
   • Remote login - enter your CData Connect Cloud username. This is displayed in the top-right corner of the CData Connect Cloud interface. For example, [email protected].
   • With password - enter the PAT you generated on the Settings page.
5. Click OK to create the server.
Your linked server can now be used to access the data in the data source you specified. If you need to access data from more sources, create another linked server for each one.

Execute Queries

You can now execute queries to the Azure Data Lake Storage linked server from any tool that can connect to SQL Server. An example SQL query would be: SELECT * FROM [CDATA CONNECT CLOUD].[ADLS1].[ADLS].[Resources] We have successfully created a linked server that allows us to query Azure Data Lake Storage data.

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