Advantages of B-tree Structure (212)

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樹結果的優點
1. 獲取索引內任何位置的資料所需的時間大致相同
2. 能夠自動保持平衡
3. 按平均數計算 ,平衡樹內的所有塊保持在3/4滿
4. 在大範圍內進行查詢時，無論是精確匹配還是搜尋一個區間（range search），都能提供優秀的查詢效能
5. 進行dml操作效率高 ， 且易於維護鍵值的順序
6. 大表小表利用平衡樹進行搜尋的效率都好，且效能不會因資料增長而降低

[@more@]