protected void initPartialInspectors(StructObjectInspector objectInspector) {
      soi = objectInspector;

      countsField = soi.getStructFieldRef("counts");
      percentilesField = soi.getStructFieldRef("percentiles");
      isAscendingField = soi.getStructFieldRef("isAscending");

      countsOI = (MapObjectInspector) countsField.getFieldObjectInspector();
      percentilesOI = (ListObjectInspector) percentilesField.getFieldObjectInspector();
    }
A state class to store intermediate aggregation results.
ql/src/java/org/apache/hadoop/hive/ql/udf/generic/GenericUDAFPercentileCont.java