@Override
    public void write(DataOutput out) throws IOException {
      // out.writeInt(numberRows);
      WritableUtils.writeVLong(out, numberRows);
      for (int i = 0; i < eachColumnValueLen.length; i++) {
        WritableUtils.writeVLong(out, eachColumnValueLen[i]);
        WritableUtils.writeVLong(out, eachColumnUncompressedValueLen[i]);
        NonSyncDataOutputBuffer colRowsLenBuf = allCellValLenBuffer[i];
        int bufLen = colRowsLenBuf.getLength();
        WritableUtils.writeVLong(out, bufLen);
        out.write(colRowsLenBuf.getData(), 0, bufLen);
      }
    }
add in a new column's meta data.

@param columnValueLen
         this total bytes number of this column's values in this split
@param colValLenBuffer
         each cell's length of this column's in this split
ql/src/java/org/apache/hadoop/hive/ql/io/RCFile.java