protected void initInspectors(
            PrimitiveObjectInspector orderByColumnOI, WritableConstantIntObjectInspector orderDirectionOI) {
      inputOI = orderByColumnOI;
      isAscending = orderDirectionOI.getWritableConstantValue().get() != DESCENDING_CODE;
    }
A state class to store intermediate aggregation results.
ql/src/java/org/apache/hadoop/hive/ql/udf/generic/GenericUDAFPercentileCont.java