SQL Server 2008 Sparse Columns - Inverses

Question

SQL Server 2008 introduces the notion of sparse columns - where only a few of a very large number of rows have a value.

We want to use this concept but the major use is to create a view where the sparse column IS NULL. Not the more usual - NOT IS NULL. Microsoft say the sparse column and associated index is optimized for retrieval of the NOT NULL rows.

Does anyone know if there is a downside to checking for the NULL condition?

Answer 1

Nice discussion here where he says

Access (read and write) to sparse columns is more expensive, but I haven't been able to find any exact figures on this.

and

As you can see from Books On-Line there is a really useful guide to when to use them for a particular data type e.g. if more than 64% of your values are null in an int column then use sparse columns, and basically the longer the data type the lower the threshold for using sparse columns.

Since this is a new feature, you should definitely do some timing tests.