need enhance feature for CBO :)

dear all, (sorry cross posting)

oracle 10.1.0.5
huge machine :)

CREATE TABLE PVC
(
  ........
  CONSTRAINT PVC_PK
 PRIMARY KEY
 (AN, SEQ, ES, ETI, ER)
)

ORGANIZATION INDEX <=== IOT :(
  PARTITION BY RANGE (SEQ)
........... (500 partitions even more)
)

NOPARALLEL; CREATE UNIQUE INDEX PVC_U1 ON PVC
(SEQ, ER)
LOCAL (
............ (500 partitions even more)
)

NOPARALLEL; there are more than billion of rows

select /*+ use_index(pvc pvc_pk) */ distinct seq from pvc;

SELECT STATEMENT ALL_ROWS
   PARTITION RANGE ALL

      SORT UNIQUE NOSORT
         INDEX FULL SCAN INDEX(UNIQUE) PVC_U1

so, my question:
- why don't oracle utilize "partition key" for this case....   (by not scanning full index will be better, because partition key based on SEQ column).
  getting list of partition key is the fastest way :) - even when force using PVC_PK, CBO won't do it, I think scanning Primary key   more efficient rather than roundtrip read PVC_U1 index and then again   read PVC_PK index, due to IOT mapping...

-- 
thanks and regards
ujang | oracle dba
jakarta | http://ora62.wordpress.com
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