GROUP BY in oData query possible?

Hello SCN!

I read the oData specification and try to use GROUP BY in my oData query on top of the Analytical View, but the result set doesn't seem to change.

If this is not possible, I have the only option to create calculation view(SQLScript) and put my group by there?

the example I tried. It simply doesn't affect the output:

/Sales?$apply=groupby((ProductName,Category))

Thank you!