code: @SuppressWarnings("rawtypes")
    @Override
  	public int compare(ITuple w1, ITuple w2) {
  		int schemaId1 = tupleMRConf.getSchemaIdByName(w1.getSchema().getName());
  		int schemaId2 = tupleMRConf.getSchemaIdByName(w2.getSchema().getName());
  		int[] indexes1 = serInfo.getGroupSchemaIndexTranslation(schemaId1);
  		int[] indexes2 = serInfo.getGroupSchemaIndexTranslation(schemaId2);
  	  Serializer[] serializers = serInfo.getGroupSchemaSerializers();
  		return compare(w1.getSchema(), groupCriteria, w1, indexes1, w2, indexes2,serializers);
  	}
docs: Never called in MapRed jobs. Just for completion and test purposes