private void reset(ColumnVector[] columns) {
    selectedInUse = false;
    size = 0;
    endOfFile = false;
    for (ColumnVector vc : columns) {
      if (vc != null) {
        vc.reset();
        vc.init();
      }
    }
  }
Resets the row batch to default state
 - sets selectedInUse to false
 - sets size to 0
 - sets endOfFile to false
 - resets each column
 - inits each column
storage-api/src/java/org/apache/hadoop/hive/ql/exec/vector/VectorizedRowBatch.java