al
    length of 20 and a partial offset of 85, the retrieval would succeed and
    the retrieved data would be the last 15 bytes of the record.
    <p>
    If the calling application is storing an item, length bytes specified
    by <tt>dlen</tt>, starting at the offset set by <tt>doff</tt>
    bytes from the beginning of the specified key's data item are replaced
    by the data specified by the DatabaseEntry.  If the partial length is
    smaller than the data, the record will grow; if the partial length