oracle表建立索引问题

[wskbuaa1984]

我有一个表A，有字段a，b，c，d，e，f，g；我以字段a进行范围分区，分了有10个区，每个区里有数据大概600万条数据左右，我常用的检索语句如下：
select * from A where a = a1 order by b;

select * from A where b between b1 and b2;

select * from A where c between c1 and c2 and b between b1 and b2;

select * from A where c between c1 and c2 and d between d1 and d2 and b between b1 and b2;

select * from A where c between c1 and c2 and d between d1 and d2 and e between e1 and e2 and b between b1 and b2;

就是字段b是常用的检索字段，但字段c，d，e，f，g等有时候用，有时候不用，用的时候也是任意几个的组合检索，
请问我在该表上应该怎么建立索引才最有效，速度最快啊？ 是应该建立全局索引还是本地索引啊？

[秋雨飘落]

分区表，如果不执行分区，就不需要建立分区索引。。

其它条件可以单独建立索引也可以建组合索引。