How can I use Oracle's CONNECT BY PRIOR to only get specific revisions of hierarchical records?
how about:

with preresult as (
SELECT id,itemname,
   linkleft,
   linkright,
   create_timestamp,
   value1,
   value2,
   ROW_NUMBER ()
      OVER (PARTITION BY itemname ORDER BY create_timestamp DESC)
      rownumber
   FROM somedata
   WHERE create_timestamp &lt; :timestamp)  
select * from preresult where rownumber &lt; 2


and enter as :timestamp the desired date and time

hth,
macfly.