Microsoft® SQL Server® 2008 Internals

Data Compression

SQL Server 2008 provides the capability of data compression, a new feature that is available in Enterprise edition only. Compression can reduce the size of your tables by exploiting inefficiencies that exist in the actual data. These inefficiencies can be grouped into two general categories. The first category relates to storage of individual data values when they are stored in columns defined using the maximum possible size. For example, a table may need to define a quantity column as int, because occasionally you may be storing values larger than 32,767, which is the maximum smallint value. However, int columns always need four bytes, and if most of your quantity values are less than 100, they could be stored in tinyint columns, ...