Hive Group By Limitations

[Peter Chu]

In Hive, I cannot perform a SELECT GROUP BY on fields not in the GROUP BY 
clause.
Example: SELECT st.a, st.b, st.c, st.d, FROM some_table st GROUP BY st.a;  -- 
This does not work.
To make it work, I would need to add the other fields in the group by clause.
Not quite sure but I think each group by will give another M/R job.
Wondering if there is any other way / better way to do group by.
Peter