public String stringify(String prefix) {
    if (size == 0) {
      return "";
    }
    StringBuilder b = new StringBuilder();
    b.append(prefix);
    b.append("Column vector types: ");
    for (int k = 0; k < projectionSize; k++) {
      int projIndex = projectedColumns[k];
      ColumnVector cv = cols[projIndex];
      if (k > 0) {
        b.append(", ");
      }
      b.append(projIndex);
      b.append(":");
      appendVectorType(b, cv);
    }
    b.append('\n');
    b.append(prefix);

    if (this.selectedInUse) {
      for (int j = 0; j < size; j++) {
        int i = selected[j];
        b.append('[');
        for (int k = 0; k < projectionSize; k++) {
          int projIndex = projectedColumns[k];
          ColumnVector cv = cols[projIndex];
          if (k > 0) {
            b.append(", ");
          }
          if (cv != null) {
            try {
              cv.stringifyValue(b, i);
            } catch (Exception ex) {
              b.append("<invalid>");
            }
          }
        }
        b.append(']');
        if (j < size - 1) {
          b.append('\n');
          b.append(prefix);
        }
      }
    } else {
      for (int i = 0; i < size; i++) {
        b.append('[');
        for (int k = 0; k < projectionSize; k++) {
          int projIndex = projectedColumns[k];
          ColumnVector cv = cols[projIndex];
          if (k > 0) {
            b.append(", ");
          }
          if (cv != null) {
            try {
              cv.stringifyValue(b, i);
            } catch (Exception ex) {
              b.append("<invalid>");
            }
          }
        }
        b.append(']');
        if (i < size - 1) {
          b.append('\n');
          b.append(prefix);
        }
      }
    }
    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