private void iterateSelectionNoNulls(
      Aggregation myagg, 
      long[] vector, 
      int batchSize, 
      int[] selected) {

    for (int i=0; i< batchSize; ++i) {
      myagg.value += vector[selected[i]];
    }
  }
class for storing the current aggregate value.
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/expressions/aggregates/VectorUDAFCountMerge.java