byte[] k = key.getBytes(UTF8);
m_writeBuf.putInt(k.length);
m_writeBuf.put(k);
ByteIterator v = columns.get(key);
int len = (int) v.bytesLeft();
m_writeBuf.putInt(len);
v.nextBuf(m_workingData, m_writeBuf.position());
m_writeBuf.position(m_writeBuf.position() + len);
}