Implementing Dynamic Row-Level Security (RLS)

Implementing Dynamic Row-Level Security (RLS) is an essential practice in Power BI to ensure that users only see the data that they are authorized to view based on their role or identity. Dynamic RLS allows you to create security rules that adapt to each user’s access level, instead of creating static roles with predefined rules.

Here’s a comprehensive guide on how to implement Dynamic Row-Level Security (RLS) in Power BI:

Step 1: Preparing Data for RLS

Before implementing RLS, you need to structure your data correctly. Typically, dynamic RLS requires the use of a security table (also called a Role Table) to define which users can access which rows of data. This table will hold the relationships between users and their allowed data.

1.1 Create a Security Table

You need a table that links users to the data they can see. This table might look like this:

Username	Region
user1@company.com	North
user2@company.com	South
user3@company.com	East

• Username: The email address or username of the user.
• Region: The field in your data model that you want to secure. This could be a region, department, country, etc.

1.2 Include the Security Table in Your Data Model

Ensure the Security Table is loaded into your Power BI data model. This table can either come from a database or be an Excel file uploaded to the Power BI model. This table will be used to filter data based on the user’s identity.

Step 2: Establish a Relationship Between the Security Table and Your Data

Now, you need to create a relationship between your Security Table and the data you want to secure (e.g., sales data, financial records).

2.1 Create Relationships

• You need to create a relationship between the Security Table and the Data Table based on the relevant column (e.g., Region).
• Ensure that the Security Table has a many-to-one relationship with your main data model.
• The Username or UserID column in the security table should be related to a similar column in your main data, like a UserID field in the data model.

Step 3: Creating the DAX Filter for Dynamic RLS

To implement dynamic filtering, you’ll need to write DAX (Data Analysis Expressions) to filter the data based on the current user’s identity. This DAX expression will check the logged-in user’s identity and filter the rows they are authorized to view.

3.1 Writing the DAX Expression for Security

You can use the USERNAME() function to capture the current logged-in user’s identity and then create a DAX expression that matches the user’s username to the Security Table.

For example, if you want to apply a security filter that restricts data based on Region:

= RELATED(SecurityTable[Username]) = USERNAME()

This expression filters the data to only show the rows where the current logged-in user’s username matches the values in the Security Table.

3.2 Applying the DAX Filter to the Data Table

• Go to the Modeling tab in Power BI Desktop.
• Click on Manage Roles.
• Create a new role for Dynamic RLS, and in the DAX formula box, paste the DAX expression that filters data based on the current user.

Step 4: Test RLS Using “View as Role” Feature

After setting up the roles and DAX filters, you can test the RLS implementation using the View as Role feature in Power BI Desktop.

4.1 Testing the Security Configuration

1. In Power BI Desktop, go to the Modeling tab.
2. Click on View as Roles.
3. Select a role (e.g., the dynamic RLS role you created).
4. Enter a Username to simulate how a particular user will see the data.

This will allow you to verify that the correct data is displayed based on the security roles you’ve defined.

Step 5: Publish the Report to Power BI Service

Once the report is working correctly in Power BI Desktop, you need to publish it to the Power BI Service to allow others to view it based on their login credentials.

5.1 Publish the Report

1. Save your Power BI file (.pbix).
2. Click on Publish in Power BI Desktop and select the workspace where you want to publish the report.
3. After publishing, you can go to the Power BI Service and manage the dataset and roles.

Step 6: Assign Users to Roles in Power BI Service

In Power BI Service, you can assign individual users or Active Directory groups to the roles you created with Dynamic RLS.

6.1 Manage Roles in Power BI Service

1. In the Power BI Service, navigate to the dataset used in your report.
2. Click on the three dots (…) next to the dataset and select Security.
3. Add users to the role by typing their names or email addresses.
4. Click Add to assign users to the role.

Step 7: Verifying RLS in Power BI Service

Once users have been assigned to their respective roles, they should automatically be filtered based on the dynamic RLS rules when they access the report.

7.1 Verify by Logging in as Users

Test by logging into the Power BI Service with different user accounts to verify that each user sees only the data they are allowed to view. The filter should be applied dynamically based on the username of the logged-in user.

Step 8: Considerations and Best Practices

• Performance Considerations: Using dynamic RLS with large datasets can affect performance. Always test with your dataset size to ensure there are no performance issues.
• Error Handling: If a user does not have a matching entry in the Security Table, you might want to handle that scenario, such as by showing them no data or a custom message.
• User Groups: Instead of assigning roles to individual users, you can assign security roles to user groups (e.g., security groups in Azure AD), which makes user management easier.

Step 9: Using Dynamic RLS with Multiple Fields

If your RLS logic involves multiple fields (e.g., Region, Department, User Role), you can extend the DAX filter expression to handle more complex conditions.

For example:

= RELATED(SecurityTable[Username]) = USERNAME() 
    && RELATED(SecurityTable[Region]) = 'North'
    && RELATED(SecurityTable[Department]) = "Sales"

This will ensure that the user can only see data for the North region and the Sales department.

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Summary

• Prepare Data: Include a security table that links users to specific data rows.
• Create Relationships: Set up the relationship between the security table and your data.
• Write DAX Filter: Use DAX to filter data dynamically based on the logged-in user.
• Test in Power BI Desktop: Use “View as Role” to test the dynamic RLS setup.
• Publish and Assign Roles: Publish the report to Power BI Service and assign roles to users.
• Verify: Test that users only see the data they are authorized to view.

By following these steps, you can successfully implement Dynamic Row-Level Security in Power BI, ensuring users can access only the data they are permitted to view based on their identity or role.