How to store OpenID Identity in DB - any recommendation?

[Vladimir]

Hello,

I read some of the previous articles about HTTP/HTTPS identities, but I'd 
like to know, if you can recommend me how to store and identify  multiple 
identities as a one single user.

We all know, that user could enter:
https://www.openidserver.com/user/
https://www.openidserver.com/user
http://www.openidserver.com/user/
http://www.openidserver.com/user
[or other variants without http/https]

in most cases refers to one single identity.

What would you recommend to webmaster? How to store an OpenID identity in 
database at this moment based on current specs?

Would this be a good/bad idea?
www.openid.com/user (without ending trailing slash and http/https?) Is this 
compatible with future OpenID development?

How do you manage this in your system?

Thanks for your suggestions,
Vlad