Should GUID be used as a foreign key to many tables

Question

I designed a database to use GUIDs for the UserID but I added UserId as a foreign key to many other tables, and as I plan to have a very large number of database inputs I must design this well.

I also use ASP Membership tables (not profiles only membership, users and roles).

So currently I use a GUID as PK and as FK in every other table, this is maybe bad design? What I think is maybe better and is the source of my question, should I add in Users table UserId(int) as a primary key and use this field as a foreign key to other tables and user GUID UserId only to reference aspnet_membership?

aspnet_membership{UserID(uniqueIdentifier)}
Users{
UserID_FK(uniqueIdentifier) // FK to aspnet_membership table
UserID(int) // primary key in this table --> Should I add this
...
}
In other tables user can create items in tables and I always must add UserId for example:
TableA{TableA_PK(int)..., CreatedBy(uniqueIdentifier)}
TableB{TableB_PK(int)..., CreatedBy(uniqueIdentifier)}
TableC{TableC_PK(int)..., CreatedBy(uniqueIdentifier)}
...

Answer 1

Ultimately the answer is that it really depends.

Microsoft have documented the performance differences of each here. While the article differs slightly to your situation, as you have to use a UNIQUEIDENTIFIER to link back to asp membership, many of the discussion points still apply.

If you have to create your own users table anyway it would make more sense to have your own int primary key, and use the GUID as a foreign key. It keeps separate entities separate. What if at some point in the future you wanted to add a different membership to a user? You would then need to update a primary key, which would have to cascade to any tables referencing this and could be quite a performance hit. If it is just a unique column in your users table it is a simple update.

Answer 2

All binary datatypes (uniqueidetifier is binary(16)) are fine as foreign keys. But GUID might cause another small problem as primary key. By default primary key is clustered, but GUID is generated randomly not sequentially as IDENTITY, so it will frequently split IO pages, that cause performance degradation a little.