Major Description
PigSecondaryKeyComparator does not implement a compare(WritableComparable a, WritableComparable b) method. In case of OrderedGroupedMergedKVInput with vertex groups, object comparison instead of byte comparison is done when merging the multiple inputs into one. Since the compare API is not overridden, WritableComparator compare API is called and the value types are directly compared which means it is always ascending.