I’m working with a database and I want to start using LINQ To SQL with it. The database doesn’t have any FKs inside of it right now for performance reasons. We are inserting millions of rows at a time to the DB which is why there aren’t any FKs.
So I’m thinking I’m going to add nonenforced FKs to the database to describe the relationships between the tables for my LINQ To SQL but I don’t want there to be a performance hit by adding nonenforced foreign keys.
Does anyone know what the effect of this might be?
Update: I’m using LINQ-To-SQL for the nonperformance intesive stuff. 80% of the data access is through stored procs on production. But for writing unit tests and other non performance critical tasks, LINQ-To-SQL makes data access really easy.
Update: Here is how you add a nonenforced FK
ALTER TABLE [dbo].[ACI] WITH NOCHECK ADD CONSTRAINT [FK_ACI_CustomerInformation] FOREIGN KEY([ACIOI]) REFERENCES [dbo].[CustomerInformation] ([ACI_OI]) NOT FOR REPLICATION GO
ALTER TABLE [dbo].[ACI] NOCHECK CONSTRAINT [FK_ACI_CustomerInformation] GO
The answer can be different for different environments (data/logs on same drive, tempdb on same drive, lots of cache vs little, etc) so the best way to find this out is to benchmark. Create two identical databases, one with fk’s and one without. Do your normal million-row-load into each database, and measure your transactions per second. That way you’ll know for sure in your own environment.