Description
There are several split related configurations, such as MAPREDMINSPLITSIZE, MAPREDMINSPLITSIZEPERNODE, MAPREDMINSPLITSIZEPERRACK, etc., that should be populated to HiveConf. Currently we only do this for MAPREDMINSPLITSIZE.
All the others, if not set, will be using the default value, which is 1.
Without these, Spark sometimes will not merge small files for file formats such as text.