To define expression dimensions users can create models in the expression tab users can write small queries to achieve the dimension. Users can validate the expression to see the preview of the data. Once everything is correct click on Done
Now in the hierarchies tab define the hierarchies mentioned in the expression. Each field will show the drop down of dimensions which also includes the expression dimensions. In the next field users can choose the next label hierarchy and so on. Save the model and then run the model.
Now in segment users can select the 1st label of hierarchy and then the corresponding measure.
For enabling drill down users can go to settings and choose drill down. Users can also choose default dimensions also.
All the dimension and measures will be clickable after the drill down is enabled
Clicking on the dimension the drill down option will be seen,clicking on it the user can see the data for the next label hierarchy. In the top users can see all the filters applied.
Now at this stage the users will have both drill up and drill down options available. Drill down will give the user the next label of hierarchy and drill up will give the user the 1st hierarchy.
When the user is at the last label of hierarchy then there will be no option of more drilling down. Users will only get the option of drill up.