Microsoft® SQL Server 2012 Unleashed

Sparse Columns: Good or Bad?

There is some disagreement in the SQL Server community whether or not sparse columns are appropriate. A number of professionals are of the opinion that any table design that requires sparse columns is a bad design that does not follow good relational design guidelines. Sparse columns, by their nature, are heavily denormalized. On the other hand, many times you have to live in the real world and make the best of a bad database design that you’ve inherited. Sparse columns can help solve performance and storage issues in databases that may have been poorly designed.

Although sparse columns can solve certain kinds of problems with database design, you should never use them as an alternative to proper database and table ...