SQL Server Analysis Services Multidimensional Modeling

Designing Roles

Designing Roles in Analysis Services

Roles are a fundamental security mechanism in SQL Server Analysis Services (SSAS). They allow you to control which users or groups can access specific data within a cube or dimension. By defining roles, you can implement row-level security, cell-level security, and dimension data security, ensuring that users only see the information relevant and permitted to them.

Understanding Role-Based Security

Role-based security in SSAS operates on the principle of assigning permissions to roles, and then assigning users or Windows groups to those roles. This approach simplifies security management, as you don't need to manage permissions individually for each user. Instead, you manage permissions for roles, and user access is determined by their role membership.

Key Concepts:

  • Permissions: Define what actions a role can perform (e.g., read data, process objects, full control).
  • Members: Users or Windows groups assigned to a role.
  • Objects: The SSAS objects (cubes, dimensions, mining structures, etc.) to which permissions are applied.

Creating and Configuring Roles

Roles are typically created and managed using SQL Server Management Studio (SSMS). Here's a general workflow:

  1. Connect to the Analysis Services Instance: Open SSMS and connect to your SSAS instance.
  2. Navigate to the Database: Expand the Databases folder and select the database containing the cube or objects you want to secure.
  3. Create a New Role: Right-click on the "Roles" folder and select "New Role...".
  4. General Settings:
    • Enter a descriptive name for the role (e.g., "Sales Manager", "Regional Sales Rep").
    • Configure the "Membership" by adding Windows users or groups.
    • Define the "Permissions" for the role. Common permissions include:
      • Read Definition: Allows users to see the metadata of objects.
      • Read Data: Allows users to query cube data.
      • Process: Allows users to process (update) cubes and dimensions.
      • Full Control: Grants all permissions.
  5. Dimension Data:

    This is where you can implement dimension data security. You can restrict access to specific members of a dimension. For example, a "Regional Sales Rep" role might only be allowed to see sales data for their specific region.

    • Select the dimension you want to secure.
    • Choose between "All Members" (default), "Selected Members", or "Custom Access".
    • For "Selected Members", you can pick specific dimension members to grant access to.
    • "Custom Access" allows you to define more complex filtering using MDX expressions.
  6. Cube Data:

    You can also restrict access to specific parts of a cube, such as particular measures or hierarchical levels. While less common for basic security, it's powerful for fine-grained control.

    • Select the cube and specify the level of access (e.g., read data).
    • Further restrictions can be applied through MDX queries, enabling cell-level security.
  7. Administrative Permissions:

    This section is for server-level permissions, typically managed by administrators and not usually configured within database roles.

  8. Save the Role: Click "OK" to save the new role.

Implementing Row-Level Security

Row-level security is achieved by filtering data based on user identity or group membership, often by leveraging dimension data security. For example:

  • Create a "Geography" dimension that includes countries, regions, and cities.
  • Create a role for "North America Sales".
  • Assign "North America Sales" role to users who should only see data from North America.
  • In the "Dimension Data" tab for the "Geography" dimension, configure the role to only allow access to members under the "North America" hierarchy level.

Implementing Cell-Level Security

Cell-level security allows you to restrict access to specific data cells within a cube, based on user context. This is typically implemented using MDX expressions in the "Cube Data" section of role configuration or through Security Roles defined at the cube level.

For example, you might want to prevent certain users from seeing the profit margin for specific products.

Note: When designing roles, thoroughly test your security configurations by logging in as users assigned to different roles to ensure they have the intended level of access.

Best Practices for Role Design

  • Principle of Least Privilege: Grant only the necessary permissions.
  • Use Windows Groups: Assign Windows groups to roles rather than individual users. This simplifies management when users join or leave the organization.
  • Organize Roles Logically: Create roles that align with job functions or data access requirements.
  • Document Your Roles: Maintain clear documentation of role definitions, permissions, and their purpose.
  • Regularly Review: Periodically review role memberships and permissions to ensure they remain appropriate.

By carefully designing and implementing roles in SSAS, you can create a secure and well-governed data environment, empowering users with the data they need while protecting sensitive information.