source: openkb.info
Oozie Launcher job is a map-only job which will start the jobs which does the real work: eg, Hive, MR, Pig, etc.
(Oozie Launcher MR job [AM/Mapper Container(Hive CLI)])
. -> (MR job-1 spawned by Hive query(stage0) [AM/Mapper/Reducer Containter])
. -> (MR job-2 spawned by Hive query(stage1) [AM/Mapper/Reducer Containter])
It is controlled by below 4 parameters set in workflow.xml for each Oozie job.