  inline void clear_temporary()
  {
    uchar *tmp= get_ptr();
    if (likely(value.ptr() == (char*) tmp))
      bzero((uchar*) &value, sizeof(value));
    else
    {
      /*
        Currently read_value should never point to tmp, the following code
        is mainly here to make things future proof.
      */
      if (unlikely(read_value.ptr() == (char*) tmp))
        bzero((uchar*) &read_value, sizeof(read_value));
    }
  }
  inline void clear_temporary()
  {
    uchar *tmp= get_ptr();
    if (likely(value.ptr() == (char*) tmp))
      bzero((uchar*) &value, sizeof(value));
    else
    {
       
      if (unlikely(read_value.ptr() == (char*) tmp))
        bzero((uchar*) &read_value, sizeof(read_value));
    }
  }