求高手优化sql 主要针对group by

SELECT r.custid custid, i.productid,
i.officialsocialprice price,
SUM(i.quanitity) amount
FROM IMEIBATCH i, RDCUST r, RDCUSTDETAIL d
WHERE (i.vendororgacode = 'ZD' OR
i.vendororgacode IN
(SELECT orgacode FROM organiza WHERE parentorgacode = 'ZD'))
AND i.provorgacode = d.orgcode
AND r.custid = d.custid

       AND i.inputdate BETWEEN TO_DATE('2013-07-15', 'YYYY-MM-DD') AND
           TO_DATE('2013-07-31', 'YYYY-MM-DD') + 1
     GROUP BY r.custid, i.productid, i.officialsocialprice

加上group by custid之后 速度明显下降！求高手指点一二

1、把查询条件中相关查询条件放到from子句后面，减少查询。
2、不用or，会查全表，你可以试一下用union 去代替。
3、在group by 和where子句的判断条件加索引等。