hash index

• 散列索引

hash index的用法和样例：

例句

1. Method will return the lowest column index.
   方法将返回最低的列索引。
2. Hashed indices can be used as an alternative to ordered indices when fast look-up is needed and sorting information is of no interest.
   当需要快速查找且不关心排序信息时，可以用散列索引来替代有序索引。