private VectorizationCondition[] createNativeConditions() {

      boolean enabled = vectorReduceSinkDesc.getIsVectorizationReduceSinkNativeEnabled();

      String engine = vectorReduceSinkDesc.getEngine();
      String engineInSupportedCondName =
          HiveConf.ConfVars.HIVE_EXECUTION_ENGINE.varname + " " + engine + " IN " +
              vectorizableReduceSinkNativeEngines;
      boolean engineInSupported = vectorizableReduceSinkNativeEngines.contains(engine);

      VectorizationCondition[] conditions = new VectorizationCondition[] {
          new VectorizationCondition(
              enabled,
              HiveConf.ConfVars.HIVE_VECTORIZATION_REDUCESINK_NEW_ENABLED.varname),
          new VectorizationCondition(
              engineInSupported,
              engineInSupportedCondName),
          new VectorizationCondition(
              !vectorReduceSinkDesc.getHasPTFTopN(),
              "No PTF TopN"),
          new VectorizationCondition(
              !vectorReduceSinkDesc.getHasDistinctColumns(),
              "No DISTINCT columns"),
          new VectorizationCondition(
              vectorReduceSinkDesc.getIsKeyBinarySortable(),
              "BinarySortableSerDe for keys"),
          new VectorizationCondition(
              vectorReduceSinkDesc.getIsValueLazyBinary(),
              "LazyBinarySerDe for values")
      };
      if (vectorReduceSinkDesc.getIsUnexpectedCondition()) {
        VectorizationCondition[] newConditions = new VectorizationCondition[conditions.length + 1];
        System.arraycopy(conditions, 0, newConditions, 0, conditions.length);
        newConditions[conditions.length] =
            new VectorizationCondition(
                false,
                "NOT UnexpectedCondition");
        conditions = newConditions;
      }
      return conditions;
    }
Returns the null order in the key columns.

@return null, which means default for all key columns, or a String
        of the same length as key columns, that consists of only "a"
        (null first) and "z" (null last).
ql/src/java/org/apache/hadoop/hive/ql/plan/ReduceSinkDesc.java