U going to use compession or not it is doesn't metter.
As i said before: MAIN PROBLEM IS LOCKS OF ROWS FROM CHILD TABLE
WHEN ORACLE UPDATE/INSERT ROW(S) FROM PARENT TABLE.

I try to explain situation again:
1. PK always use B+ tree index.
2. this type of index consists from banch and leaf nodes.

3. if u place FK fields last then:
================================
* First levels of tree:
* keep information from pk field of child table only!
-----------------------------------------
* Last levels of tree
* keep information from FK field of child table (or pk fields of parent table)
================================
ORACLE CAN'T USE THIS INDEX FOR LOCK ROWS ON THE CHILD TABLE
WHEN IT UPDATE/DELETE ROW(S) IN PARENT TABLE.
ORACLE HAVE TO LOCK !!!ALL ROWS OF CHILD TABLE.

4. if u place FK fields first THEN:
================================
* First levels of tree:
* keep information from FK field of child table
-----------------------------------------
* Last levels of tree
* keep information from pk field of child table
================================
oracle can use trhis index for lock,
but ORACKE HAVE TO MAKE ADDITION READS FOR FOR GET
EACH "CLEAR" PK OF A CHILD TABLE.



[Edited by Shestakov on 07-18-2002 at 01:47 PM]