test=*# select * from pfump ;
 id | parent |   value
----+--------+-----------
  1 |        | MS Office
  2 |      1 | Excel
  3 |      1 | Word
  4 |        | Win XP
  5 |      4 | Explorer
  6 |      5 | Dateien
  7 |      5 | Desktop
  8 |      4 | Registry
  9 |      4 | System
 10 |      9 | Boot
 11 |      9 | Netzwerk
 12 |        | Win 7
 13 |     12 | Explorer
 14 |     13 | Dateien
 15 |     13 | Desktop
 16 |     12 | Registry
 17 |     12 | System
(17 rows)

test=*# with recursive r as (select id, parent, value, 0 as count from pfump where parent is null union all select p.id, p.parent, p.value, r.count+1 from pfump p, r where r.id=p.parent) select repeat('-',count)||'>',value from r order by id;
 ?column? |   value
----------+-----------
 >        | MS Office
 ->       | Excel
 ->       | Word
 >        | Win XP
 ->       | Explorer
 -->      | Dateien
 -->      | Desktop
 ->       | Registry
 ->       | System
 -->      | Boot
 -->      | Netzwerk
 >        | Win 7
 ->       | Explorer
 -->      | Dateien
 -->      | Desktop
 ->       | Registry
 ->       | System
(17 rows)

with
  recursive r
as (
  select
    id,
    parent,
    value,
    0 as count
  from
    pfump
  where
    parent is null
  union all
  select
    p.id,
    p.parent,
    p.value,
    r.count+1
  from
    pfump p,
    r
  where
    r.id=p.parent
)
select
  repeat('-',count)||'>',
  value
from
  r
order by
  id;