Thanks James for your answer,
I'm fairly new to freeradius I know the package only 14 days. (or
radius in general for that matter)
The group configuration is a mystery to me. It is unclear for me how
this separates the users. This is how I think
1) G1 with users A,B,C
2) G2 with users X,Y,Z
3) At a request the configuration determines which group the user
belongs to
4) And makes a query for the users A until Z to the same database
5) the auth_query only talks about the user.
6) This is the point where a fail to understand that the group config
helps me. The query is made to the same database on behalf of the any
user.
Please spell it out to me where my thinking goes wrong. I would like
the understand this group config thing better (if at all at this point
in time).