How long will it be between logins for any user? If it is very long, all content since last login would be impractical anyway - there would be too much new content for such a feature to be useful. If it isn't long, you can just delete log entries older than, say, twice the average time between logins or something like that. 
<br><br><div><span class="gmail_quote">On 5/3/07, <b class="gmail_sendername">Jason Flatt</b> &lt;<a href="mailto:drupal@oadaeh.net">drupal@oadaeh.net</a>&gt; wrote:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
On Thursday May 3 2007 10:23 am, Haisam K. Ido wrote:<br>&gt; uid=$uid<br>&gt;<br>&gt; $sql = &quot;SELECT node.uid,watchdog.timestamp, node.changed FROM<br>&gt; `watchdog`,node where watchdog.message like \&#39;Session closed for%\&#39; AND
<br>&gt; node.changed &gt;= watchdog.timestamp and node.uid=watchdog.uid and<br>&gt; node.uid=$uid&quot;;<br>&gt;<br>&gt; I believe that the above query returns all nodes which have changed<br>&gt; since $uid&#39;s last login.
<br>&gt;<br><br>So I guess you have your site configured to never delete any log entries?<br><br>admin/settings/error-reporting<br><br>--<br>Jason Flatt<br><a href="http://www.oadaeh.net/">http://www.oadaeh.net/</a><br>Father of Six:&nbsp;&nbsp;
<a href="http://www.flattfamily.com/">http://www.flattfamily.com/</a> (Joseph, 13; Cramer, 11; Travis,<br>9; Angela; Harry, 5; and William, 12:04 am, 12-29-2005)<br>Linux User:&nbsp;&nbsp;&nbsp;&nbsp; <a href="http://www.kubuntu.org/">http://www.kubuntu.org/
</a><br>Drupal Fanatic: <a href="http://drupal.org/">http://drupal.org/</a><br>--<br>[ Drupal support list | <a href="http://lists.drupal.org/">http://lists.drupal.org/</a> ]<br></blockquote></div><br>