why the index is not used ?

From: Kevin Tsay <Kevin_Tsay_at_liz.com>
Date: Wed, 26 Apr 2000 14:36:49 -0700
Message-Id: <10479.104218@fatcity.com>

Hi listers:

I've a simple parent-child relationship query:

SELECT T.BUSINESS_UNIT_ID, T.TRANSFER_ID, T.TRANSFER_OCCURENCE_TYPE, T.TRANSFER_TYPE, T.FROM_SITE_ID, T.TO_SITE_ID, TD.TRANSFER_DETAIL_ID, TD.LINE_NO, TD.ITEM_QTY
FROM TRANSFERS T, TRANSFER_DETAILS TD

WHERE T.BUSINESS_UNIT_ID=TD.BUSINESS_UNIT_ID
AND   T.TRANSFER_ID=TD.TRANSFER_ID
AND   T.TRANSFER_OCCURENCE_TYPE=TD.TRANSFER_OCCURENCE_TYPE;

Table TRANSFERS has PRIMARY KEY ( BUSINESS_UNIT_ID, TRANSFER_ID, TRANSFER_OCCURENCE_TYPE )
Table TRANSFER_DETAILS has PRIMARY KEY ( BUSINESS_UNIT_ID, TRANSFER_ID, TRANSFER_OCCURENCE_TYPE, TRANSFER_DETAIL_ID ) & referential constraint on TRANSFERS and the explain plans are:

SELECT STATEMENT Optimizer=CHOOSE (Cost=13605 Card=923364 Bytes=129270960)

    MERGE JOIN (Cost=13605 Card=923364 Bytes=129270960)     SORT (JOIN)
        TABLE ACCESS (FULL) OF TRANSFERS (Cost=274 Card=126961 Bytes=9268153)     SORT (JOIN)
        TABLE ACCESS (FULL) OF TRANSFER_DETAILS (Cost=1524 Card=923363 Bytes=61865321)

My question is why the primary key index is not used ?

ORACLE: 7.3.4.3 HP-UX
Both tables have been analyzed (compute)?

Any insights ? Received on Wed Apr 26 2000 - 16:36:49 CDT