Roles

Articol
10/29/2024

Applies to: SQL Server Analysis Services Azure Analysis Services Fabric/Power BI Premium

Roles in tabular models define member permissions for a model. Members of the role can perform actions on the model as defined by the role permission. Roles defined with read permissions can also provide more security at the row-level by using row-level filters.

For Azure Analysis Services and Power BI semantic models, users must be in your Microsoft Entra ID. Usernames and groups are specified by organizational email address or user principal name (UPN). For SQL Server Analysis Services, roles contain user members specified by Windows username or by Windows group, and permissions (read, process, administrator).

Important

If you use Visual Studio to create roles and add users to a tabular model project that will be deployed to Azure Analysis Services or Power BI, use Integrated workspace.

Important

For users to connect to a deployed model by using a reporting client application, you must create at least one role that has at least Read permission. Add users of the reporting client app to the role as members.

Information in this article is meant for tabular model authors who define roles by using the Role Manager dialog box in SSDT. Roles defined during model authoring apply to the model workspace database. After a model database is deployed, model database administrators can manage (add, edit, delete) role members by using SSMS.

Understanding roles

Roles are used in Analysis Services to manage model data access. There are two types of roles:

The server role is a fixed role that provides administrator access to an Analysis Services server instance. Server roles don't apply to Power BI. Instead, Power BI uses workspace roles.
Database roles are defined by model authors and administrators to control access to a model database and data for users.

Roles defined for a tabular model are database roles. These roles contain users or groups that have specific permissions that define the action those members can take on the model database. A role is created as a separate object in the database, and applies only to the database that the role is created in. The model author adds users and groups to the role. By default, the model author has Administrator permissions on the workspace database server; for a deployed model, role members are added by an administrator.

Roles in tabular models can be further defined with row filters, also known as row-level-security. Row filters use DAX expressions to define the rows in a table, and any related rows in the many direction, that a user can query. Row filters using DAX expressions can only be defined for the Read and Read and Process permissions. In Power BI, model roles are defined in Power BI Desktop and apply only to row-level security. To learn more, see Row filters later in this article.

By default, when you create a new tabular model project, the project doesn't have any roles defined. Roles are defined by using the Role Manager dialog box in SSDT. When roles are defined during model authoring, they are applied to the model workspace database. When the model is deployed, the same roles are applied to the deployed model. After a model is deployed, members of the server role (Analysis Services Administrator) and database administrators can manage the roles associated with the model and the members associated with each role by using SSMS.

Permissions

Role permissions described in this section apply only to Azure Analysis Services and SQL Server Analysis Services. In Power BI, permissions are defined for the semantic model. To learn more, see Manage semantic model access.

Each role has a single defined database permission (except for the combined Read and Process permission). By default, a new role has the None permission. When members are added to a role that has the None permission, they can't modify the database, run a process operation, query data, or see the database unless a different permission is granted.

A group or user can be a member of any number of roles, each role having a different permission. When a user is a member of multiple roles, the permissions defined for each role are cumulative. For example, if a user is a member of a role with the Read permission, and also a member of a role with None permission, that user has Read permissions.

Each role can have one the following permissions defined:

Permissions	Description	Row filters using DAX
None	Members can't make any changes to the model database schema and can't query data.	Row filters don't apply. No data is visible to users in this role
Read	Members are allowed to query data (based on row filters) but can't see the model database in SSMS, can't make any changes to the model database schema, and the user can't process the model.	Row filters can be applied. Only data specified in the row filter DAX formula is visible to users.
Read and Process	Members are allowed to query data (based on row-level filters) and run process operations by running a script or package that contains a process command, but can't make any changes to the database. Users with permission can't view the model database in SSMS.	Row filters can be applied. Only data specified in the row filter DAX formula can be queried.
Process	Members can run process operations by running a script or package that contains a process command. Members can't modify the model database schema, can't query data, and can't query the model database in SSMS.	Row filters don't apply. No data can be queried in this role
Administrator	Members can make modifications to the model schema and can query all data in the model designer, reporting client, and SSMS.	Row filters don't apply. All data can be queried in this role.

Note

Members with Read and Read and Process permissions can query data based on row filters but can't see the model database in SSMS. Members can't make changes to the model database schema and can't process the model. However, in SQL Server Analysis Services 2019 and earlier, members can use DMVs to determine measure definitions. SQL Server Analysis Services 2022 and later block access to DMVs for improved security.

Row filters

Row filters, commonly known as row-level security in Power BI, define which rows in a table can be queried by members of a particular role. Row filters are defined for each table in a model by using DAX formulas.

Row filters can be defined only for roles with Read and Read and Process permissions. By default, if a row filter is not defined for a particular table, members of a role that has Read or Read and Process permission can query all rows in the table unless cross-filtering applies from another table.

After a row filter is defined for a particular table, a DAX formula that evaluates to a TRUE/FALSE value, defines the rows that can be queried by members of that particular role. Rows not included in the DAX formula can't be queried. For example, for members of the Sales role, if the Customers table has the following row filters expression, =Customers [Country] = "USA", then members of the Sales role will only see customers in the USA.

Row filters apply to the specified rows as well as related rows. When a table has multiple relationships, filters apply security for the relationship that is active. Row filters will be intersected with other row filers defined for related tables, for example:

Table	DAX expression
Region	=Region[Country]="USA"
ProductCategory	=ProductCategory[Name]="Bicycles"
Transactions	=Transactions[Year]=2020

The net effect of these permissions on the Transactions table is that members can query rows of data where the customer is in the USA, and the product category is bicycles, and the year is 2020. Users can't query any transactions outside of the USA, or any transactions that are not bicycles, or any transactions not in 2020 unless they are a member of another role that grants these permissions.

You can use the filter, =FALSE(), to deny access to all rows for an entire table.

To learn more about model roles in Power BI, see row-level security in Power BI.

Dynamic security

Dynamic security lets you define row-level security based on the username of the user currently logged on or the CustomData property returned from a connection string. To implement dynamic security, you must include a table with login (Windows user name) values for users as well as a field that can be used to define a particular permission in your model. For example, include a dimEmployees table with a login ID (domain\username) as well as a department value for each employee in the model.

To implement dynamic security, you can use the following functions as part of a DAX formula to return the username of the user currently logged on, or the CustomData property in a connection string:

Function	Description
USERNAME Function (DAX)	Returns the domain\username of the user currently logged on.
CUSTOMDATA Function (DAX)	Returns the CustomData property in a connection string.

You can use the LOOKUPVALUE function to return values for a column where the Windows username is the same as the username returned by the USERNAME function or a string returned by the CustomData function. Queries can be restricted where the values returned by LOOKUPVALUE match values in the same or related table.

For example, using this formula:

='dimDepartment'[DepartmentId]=LOOKUPVALUE('dimEmployees'[DepartmentId], 'dimEmployees'[LoginId], USERNAME(), 'dimEmployees'[LoginId], 'dimDepartment'[DepartmentId])

The LOOKUPVALUE function returns values for the dimEmployees[DepartmentId] column where the dimEmployees[LoginId] is the same as the LoginID of the user currently logged on, returned by USERNAME, and values for dimEmployees[DepartmentId] are the same as values for dimDepartment[DepartmentId]. The values in DepartmentId returned by LOOKUPVALUE are then used to restrict the rows queried in the dimDepartment table, and any tables related by DepartmentId. Only rows where DepartmentId are also in the values for the DepartmentId returned by LOOKUPVALUE function are returned.

dimEmployees

LastName	FirstName	LoginId	DepartmentName	DepartmentId
Brown	Kevin	Adventure-works\kevin0	Marketing	7
Bradley	David	Adventure-works\david0	Marketing	7
Dobney	JoLynn	Adventure-works\JoLynn0	Production	4
Baretto DeMattos	Paula	Adventure-works\Paula0	Human Resources	2

dimDepartment

DepartmentId	DepartmentName
1	Corporate
2	Executive General and Administration
3	Inventory Management
4	Manufacturing
5	Quality Assurance
6	Research and Development
7	Sales and Marketing

Testing roles

When creating a model project in Visual Studio, you can use the Analyze in Excel feature to test the efficacy of the roles you have defined. From the Model menu in the model designer, select Analyze in Excel. Before Excel opens, the Choose Credentials and Perspective dialog box appears. In this dialog, you can specify the current username, a different username, a role, and a perspective that you will use to connect to the workspace model as a data source. To learn more, see Analyze in Excel.

Scripting roles

Roles for deployed models and semantic models can be scripted by using Tabular Model Scripting Language (TMSL) to create or modify the Roles object. TMSL scripts can be executed in SSMS or with the Invoke-ASCmd PowerShell cmdlet.

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