v$undostat question

Oracle 9.2.0.8

How is it possible for maxquerylen to go from 1 to 9000 in a single 10 minute interval? Is this a bug? Can't find anything about it on metalink. TIA

SELECT begin_time,

    end_time,
    maxquerylen
FROM v$undostat
WHERE begin_time BETWEEN
to_date('10-FEB-08 19:19:19', 'dd-mon-yy hh24:mi:ss') AND
to_date('10-FEB-08 19:29:19', 'dd-mon-yy hh24:mi:ss') ORDER BY begin_time;

BEGIN_TIME END_TIME MAXQUERYLEN

------------------ ------------------ -----------
10-FEB-08 19:19:19 10-FEB-08 19:29:19           1
10-FEB-08 19:29:19 10-FEB-08 19:39:19        9387

2 rows selected Received on Wed Feb 13 2008 - 09:00:00 CST