In Tableau, multidimensional data sources are supported only in Windows.Aliases for multidimensional databases are created on the server by the server administrator and can be activated in Tableau using the Alias File option on the Data menu. Please talk to your database administrator to find out whether your database has aliases available. Aliases are not support by Microsoft Analysis Services databases.
By default the alias for every member of every dimension is initially defined to be the original member name. For example, the figure below shows a bar chart built from an Essbase database. By default, the original member names are displayed (example on the left). As you can see, these names are not very intuitive. By selecting and selecting an appropriate alias file set up by the database administrator, meaningful names are displayed in the headers.