Why & When should I use SPARSE COLUMN? (SQL SERVER 2008)

Question

After going thru some tutorials on SQL Server 2008\'s new feature \"SPARSE COLUMN\", I have found that it doesn\'t take any space if the column value is 0 or NULL but when t

Answer 1

You're reading it wrong - it never takes 4x the space.

Specifically, it says 4* (4 bytes, see footnote), not 4x (multiply by 4). The only case where it's exactly 4x the space is a char(4), which would see savings if the NULLs exist more than 64% of the time.

"*The length is equal to the average of the data that is contained in the type, plus 2 or 4 bytes."