private void assignStringNoNullsNoRepeatingNoSelection(int index, int size,
      BytesColumnVector columnVector) {
    for(int i=0; i<size; ++i) {
      vectorHashKeyWrappers[i].assignString(
          index,
          columnVector.vector[i],
          columnVector.start[i],
          columnVector.length[i]);
    }
  }
Helper method to assign values from a vector column into the key wrapper.
Optimized for double type, no nulls, no repeat values, no selection vector.
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/wrapper/VectorHashKeyWrapperBatch.java