What part of LINQ to SQL's provider model makes it impossible to extend it to support third party (read: Non-Microsoft) databases?

Question

There were supposedly some classes in the LINQ to SQL provider model that were sealed--but I never really figured out exactly which classes need to be 'unsealed' in order to use it.

Hypothetically speaking, which classes do I need to unseal to enable the provider model?

[EDIT: I know that the sealed keyword means that it's not supposed to be modified, but let's just assume that unsealing a BCL class is not the issue here.]

Answer 1

You can create your own LINQ provider. It wouldn't be a LINQ to SQL provider though, it would be a LINQ to [whatever] provider.

More details at: http://dotnetslackers.com/articles/csharp/LINQProviderBasics.aspx

Or you could check out the DB Link Project: http://code2code.net/DB_Linq/