public String stringifyColumn(int columnNum) {
    if (size == 0) {
      return "";
    }
    StringBuilder b = new StringBuilder();
    b.append("columnNum ");
    b.append(columnNum);
    b.append(", size ");
    b.append(size);
    b.append(", selectedInUse ");
    b.append(selectedInUse);
    ColumnVector colVector = cols[columnNum];
    b.append(", noNulls ");
    b.append(colVector.noNulls);
    b.append(", isRepeating ");
    b.append(colVector.isRepeating);
    b.append('\n');

    final boolean noNulls = colVector.noNulls;
    final boolean[] isNull = colVector.isNull;
    if (colVector.isRepeating) {
      final boolean hasRepeatedValue = (noNulls || !isNull[0]);
      for (int i = 0; i < size; i++) {
        if (hasRepeatedValue) {
          colVector.stringifyValue(b, 0);
        } else {
          b.append("NULL");
        }
        b.append('\n');
      }
    } else {
      for (int i = 0; i < size; i++) {
        final int batchIndex = (selectedInUse ? selected[i] : i);
        if (noNulls || !isNull[batchIndex]) {
          colVector.stringifyValue(b, batchIndex);
        } else {
          b.append("NULL");
        }
        b.append('\n');
      }
    }
    return b.toString();
  }
Return count of qualifying rows.

@return number of rows that have not been filtered out
storage-api/src/java/org/apache/hadoop/hive/ql/exec/vector/VectorizedRowBatch.java