private void serialize(int pos, byte[] bytes, int start, int length) throws IOException {
    serializeWrite.setAppend(output);
    serializeWrite.writeString(bytes, start, length);
    int outputNewPosition = output.getLength();
    serializedKeyLengths[pos] = outputNewPosition - outputStartPosition;
    outputStartPosition = outputNewPosition;
  }
A key series of a single column of byte array keys where the keys get serialized.
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/keyseries/VectorKeySeriesBytesSerialized.java