public static void addRandomNulls(ColumnVector col) {
    col.noNulls = false;
    Random rand = new Random();
    for(int i = 0; i != col.isNull.length; i++) {
      col.isNull[i] = Math.abs(rand.nextInt() % 11) == 0;
    }
  }
Sprinkle null values in this column vector.

@param col
ql/src/test/org/apache/hadoop/hive/ql/exec/vector/TestVectorizedRowBatch.java