procedure p1()--resides in db1
is
begin
....
select col1 from table1@db2;

...
end
/

SELECT do.obj#                                          d_obj, 
       do.name                                          d_name, 
       do.type#                                         d_type, 
       po.obj#                                          p_obj, 
       po.name                                          p_name, 
       To_char(p_timestamp, 'DD-MON-YYYY HH24:MI:SS')   "P_Timestamp", 
       To_char(po.stime, 'DD-MON-YYYY HH24:MI:SS')      "STIME", 
       Decode(Sign(po.stime - p_timestamp), 0, 'SAME', 
                                            '*DIFFER*') X 
FROM   sys.obj$ do, 
       sys.dependency$ d, 
       sys.obj$ po 
WHERE  p_obj# = po.obj#(+) 
       AND d_obj# = do.obj# 
       AND do.status = 1 /*dependent is valid*/ 
       AND po.status = 1 /*parent is valid*/ 
       AND po.stime != p_timestamp /*parent timestamp not match*/ 
       AND po.owner# <> 0 
ORDER  BY 2, 
          1;