...
Chooses execution engine. Options are: mr
(Map reduceReduce, default), tez
(Tez execution, for Hadoop 2 only), or spark
(Spark execution, for Hive 1.1.0 onward).
While mr
remains the default engine for historical reasons, it is itself a historical engine and is deprecated in the Hive 2 line (HIVE-12300). It may be removed without further warning.
See Hive on Tez and Hive on Spark for more information, and see the Tez section and the Spark section below for their configuration properties.
...