我正在为表生成代理键，由于我的hi / lo算法，每次重新启动/重新启动计算机时，可能会出现间隙。

T1: current hi = 10000000 
    (sequence being dished out .. 1 to 100)
       Assume that current sequence is 10000050

T2: restart system.

T3: System gives out the next_hi as 10000100 
    (sequence being dished out now ranges from 101 to 200)

T4: Next request for a key returns 100001001

从主键或索引内部结构的角度来看，序列中没有间隙为什么很重要？我问这是为了更深入地了解mysql。