Here's what the most recent version of the CDH Hive documentation says about this:
"Transaction (ACID) Support in Hive
The CDH distribution of Hive does not support transactions (HIVE-5317). Currently, transaction support in Hive is an experimental feature that only works with the ORC file format. Cloudera recommends using the Parquet file format, which works across many tools. Merge updates in Hive tables using existing functionality, including statements such as INSERT, INSERT OVERWRITE, and CREATE TABLE AS SELECT."