I can't figure out how it's working. Like this. How is this get page number -and records- by post id?

I think the first option is; declare an index / int variable in post table and increase-decrease it when adding and deleting post. but whats happen when i delete first row and if table has one million records?

Do you have any idea about this? by the way, i'm using nhibernate and sql server 2005.

Thank you