For a primary key of an integral type, why is it important to avoid gaps?

Question

I am generating a surrogate key for a table & due to my hi/lo algorithm, everytime you reboot/restart the machine, gaps may appear.

T1: current hi = 10000000         


        

Answer 1

why is it important that there be no gaps in the sequences

It is not important. Gaps are fine. For performance reasons, gaps are tolerated.

What would be useful is a guarantee to have an strictly increasing sequence (i.e. the sequence has the same ordering as the row creation time). But even that is not guaranteed in a clustered configuration (with local counter caches).