Celko and Sean,

Thanks for the responses, I'm sorry i don't think i was clear enough, what I have is something like

ID ParentID Hierarchy

1 NULL 1

2 1 1.2

3 2 1.2.3

4 1 1.4

...

what first querie does is a like on Hierarchy column, what mine does is a rcte from ID to ParentID pretty much like BOL examples... what I really don't understand is why query optimizer tells me the rcte is cheaper execution wise whilst it produces way more IO and CPU time than the like approach, by that i mean that this :

SELECT

stChild.OUID,

stChild.OUParentID,

stChild.CustomerID,

stChild.Name,

stChild.NameFull,

stChild.Hierarchy,

stChild.HierarchyDepth,

stChild.Enabled,

st.OUID as OUIDAncestor

FROM SomeTable st

INNER JOIN SomeTable stChild ON stChild.Hierarchy + '.' LIKE st.Hierarchy + '.%'

produces less IO and CPU time than a cookie cutter rcte having a anchor on top-level rows and recursing on childs

Edit : just setting sql code in the right container ( was in a quote )