Hive and Impala do not support combination of SELECT DISTINCT and GROUP BY in one SQL query.

Messages of exceptions:
Impala - cannot combine SELECT DISTINCT with aggregate functions or GROUP BY
Hive - SELECT DISTINCT and GROUP BY can not be in the same query. 

DDL:
CREATE VIEW Agg2 (StringNum string)
  AS SELECT BQT1.SmallA.StringNum FROM BQT1.SmallA GROUP BY BQT1.SmallA.StringNum HAVING BQT1.SmallA.StringNum = '1';
Query:
SELECT DISTINCT StringNum FROM VQT.Agg2