SQL & PL/SQL

Dear All,

I have the following query but it is taking too much time because of the LEFT OUTER JOIN on HST table which is a huge table , is there an alternative to LEFT OUTER JOIN that can be used to optimize the code:

SELECT HST.COMP_CODE,
HST.BRANCH_CODE,
HST.CURRENCY_CODE,
HST.GL_CODE,
HST.CIF_SUB_NO,
HST.SL_NO,
SUM(CV_AMOUNT) CV_AMOUNT,
MAX(NVL(I.LAST_NO, HST.OP_NO) + 1) OP_NO,
MAX(BC_FLAG) BC_FLAG,
MAX(OP_STATUS) OP_STATUS,
SUM(FC_AMOUNT) FC_AMOUNT
FROM HST HST
LEFT OUTER JOIN IBISCOUNTER I
ON I.COMP_CODE = HST.COMP_CODE
AND I.BRANCH_CODE = HST.BRANCH_CODE
AND I.TRX_TYPE = 'DOF'
WHERE (HST.VALUE_DATE <= TO_DATE('31/12/2010', 'DD/MM/YYYY')
AND HST.TRANS_DATE <= TO_DATE('31/12/2010', 'DD/MM/YYYY'))
AND LINE_NO > 0
GROUP BY HST.COMP_CODE, HST.BRANCH_CODE, HST.CURRENCY_CODE, HST.GL_CODE, HST.CIF_SUB_NO, HST.SL_NO