An important requirement for some applications to be efficient is the ability to query for data that has changed in a database. Typically, to determine data changes, application developers had to implement a custom tracking method in their applications by using a combination of triggers, timestamp columns, and additional tables. Creating these applications usually involved a lot of work to implement, led to schema updates, and often carried a high performance overhead.

SQL Server 2008 provides the following new technologies that application developers can use to track data changes and enable applications to query for only the data that has changed:

• Change data capture
  
• Change tracking