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

From SQL SERVER – 2008 – Introduction to SPARSE Columns – Part 2 by Pinal Dave:

All SPARSE columns are stored as one XML column in database. Let us see some of the advantage and disadvantage of SPARSE column.

Advantages of SPARSE column are:

• INSERT, UPDATE, and DELETE statements can reference the sparse columns by name. SPARSE column can work as one XML column as well.

• SPARSE column can take advantage of filtered Indexes, where data are filled in the row.

• SPARSE column saves lots of database space when there are zero or null values in database.

Disadvantages of SPARSE column are:

• SPARSE column does not have IDENTITY or ROWGUIDCOL property.

• SPARSE column can not be applied on text, ntext, image, timestamp, geometry, geography or user defined datatypes.

• SPARSE column can not have default value or rule or computed column.

• Clustered index or a unique primary key index can not be applied SPARSE column. SPARSE column can not be part of clustered index key.

• Table containing SPARSE column can have maximum size of 8018 bytes instead of regular 8060 bytes. A table operation which involves SPARSE column takes performance hit over regular column.