HIVE-5861: Fix exception in multi insert statement on Tez (Gunther Hagleitner)

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/tez@1543957 13f79535-47bb-0310-9956-ffa450edef68
HIVE-5862: While running some queries on large data using tez, we OOM. (Vikram Dixit K via Gunther Hagleitner)

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/tez@1543978 13f79535-47bb-0310-9956-ffa450edef68