HIVE-7063 : Optimize for the Top N within a Group use case (Harish Butani via Ashutosh Chauhan)

git-svn-id: https://svn.apache.org/repos/asf/hive/trunk@1606775 13f79535-47bb-0310-9956-ffa450edef68
HIVE-2597 : Repeated key in GROUP BY is erroneously displayed when using DISTINCT (Navis via Ashutosh Chauhan)

git-svn-id: https://svn.apache.org/repos/asf/hive/trunk@1606780 13f79535-47bb-0310-9956-ffa450edef68