Hi,
I read couple of articles that talk about primary key, and it mentioned that we should use integer as primary key and don try to re-use it. If we need something unique such as ID number or customer code, we could place it as candicate key. It is the same effect.

I am not very clear about:
1. Since, filtered index is not optimize, how am I going to re-use the deleted candicate key but not effect the speed?

2. If I have a auto-generated field like Invoice No., do yoo think it is good to be primary key or candicate key??

Thank you