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);
}
byte[] data = new byte[m_writeBuf.position()];
System.arraycopy(m_workingData, 0, data, 0, data.length);