Branch blocks store the following: ■ The minimum key prefix needed to make a branching decision between two keys ■ The pointer to the child block containing the key If the blocks have n keys then they have n+1 pointers. The number of keys and pointers is limited by the block size. 分支块 分之块存储以下信息 1. 最小的键值前缀 ， 在两个键值之间做出分支选择 2. 指向包含所查找键值的子块的指针 包含n个键值的分支块对应有n+1个指针 。键值和指针数有块大小所限制[@more@]