What is the cost in bytes for the overhead of a sql_variant column in SQL Server?

Question

I have a table, which contains many columns of float data type with 15 digit precision. Each column consumes 8 bytes of storage. Most of the time the data does not require this amount of precision and could be stored as a real data type. In many cases the value can be 0, in which case I could get away with storing a single byte.

My goal here is to optimize space storage requirements, which is an issue I am facing working with a SQL Express 4GB database size limit.

If byte, real and float data types are stored in a sql_variant column there is obviously some overhead involved in storing these values. What is the cost of this overhead?

I would then need to evaluate whether I would actually end up in significant space savings (or not) switching to using sql_variant column data types.

Thanks, Elan

Answer 1

I found the folowing article very useful in shedding light on the cost of storage as far as sql_variant is concerned:

http://msdn.microsoft.com/en-us/library/ms178085.aspx