在B+树中，如果搜索关键字值为8字节，块大小为512字节，块指针为2字节，则B+树的最大阶数为____。
注意：此问题显示为数字答案类型。
(一) 51
(乙) 52
(三) 53
(四) 54答案：(乙)
解释：
Order of a B+ tree node is maximum number of children
in an internal node
Let the order be x. Number of keys in a node is equal to
number children minus 1.
So a full node has (x-1) keys and x children.
(x-1)*(search key) + x * block ptr <= block size
==> (x-1)*8 + x*2 <= 512
==> 10x <= 520
==> x <= 52这个问题的测验