doing a retrieval, length bytes specified by
    <tt>dlen</tt>, starting at the offset set by <tt>doff</tt> bytes from
    the beginning of the retrieved data record are returned as if they
    comprised the entire record.  If any or all of the specified bytes do
    not exist in the record, the get is successful, and any existing bytes
    are returned.
    <p>
    For example, if the data portion of a retrieved record was 100 bytes,
    and a partial retrieval was done using a DatabaseEntry having a parti