Well, that's the *theory*.  In practice, I've found that something that
kills the server without a clean HALT can leave one partly written.  At
least on a single-threaded server, the updates seem to be done
sequentially.  So it's possible for a half record to be written to one
before the other is touched.

      /
  /  *  /  Alan Hamilton
 *     *   alanh AT primenet DOT com