Query Performance with NULL

Question

I would like to know about how NULL values affect query performance in SQL Server 2005.

I have a table similar to this (simplified):

ID | ImportantDa         


        

Answer 1

NULL looks good to me as well. SQL Server has many kinds of indices to choose from. I forget which ones do this, but some only index values in a given range. If you had that kind of index on the column being tested, the NULL valued records would not be in the index, and the index scan would be fast.