Index not used when select contain *

I've this problem:

i've create an index with 4 field
CREATE UNIQUE INDEX AOS_INDEX_LNK23_X_LAS ON LNK23_RICHIESTA_SIS_EST (L23_STATO, L23_DATAORA_RICH, L23_NUM_RICHIESTA, L23_NUM_EPISODIO) The table contain 20 field and the primary key is: PRIMARY KEY (L23_DATAORA_RICH, L23_NUM_RICHIESTA, L23_NUM_EPISODIO) with this: query:
SELECT L23_STATO, L23_DATAORA_RICH, L23_NUM_RICHIESTA, L23_NUM_EPISODIO FROM GSTUSER.LNK23_RICHIESTA_SIS_EST
WHERE L23_STATO='C'
the index is used

but with this
SELECT *
FROM GSTUSER.LNK23_RICHIESTA_SIS_EST
WHERE L23_STATO='C'
the index in not ued.
Please, can you tell me where is the problem? Received on Mon Sep 11 2006 - 03:46:16 CDT