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Advantages of B-tree Structure (212)

原创 IT综合 作者:tsinglee 时间:2007-11-16 10:21:25 0 删除 编辑

The B-tree structure has the following advantages:
■ All leaf blocks of the tree are at the same depth, so retrieval of any record from
anywhere in the index takes approximately the same amount of time.
■ B-tree indexes automatically stay balanced.
■ All blocks of the B-tree are three-quarters full on the average.
■ B-trees provide excellent retrieval performance for a wide range of queries,
including exact match and range searches.
■ Inserts, updates, and deletes are efficient, maintaining key order for fast retrieval.
■ B-tree performance is good for both small and large tables and does not degrade as
the size of a table grows.

B树结果的优点
1. 获取索引内任何位置的数据所需的时间大致相同
2. 能够自动保持平衡
3. 按平均数计算 ,平衡树内的所有块保持在3/4满
4. 在大范围内进行查询时,无论是精确匹配还是搜索一个区间(range search),都能提供优秀的查询性能
5. 进行dml操作效率高 , 且易于维护键值的顺序
6. 大表小表利用平衡树进行搜索的效率都好,且性能不会因数据增长而降低

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