SQL Server Change Data Capture – A Comprehensive Overview

 Microsoft launched its SQL Server CDC product in 2005 with several cutting-edge and technologically advanced features, such as “after update”, “after insert”, and “after delete” abilities. Since this technology was very complex and not received well by DBAs, Microsoft released a revised and more advanced version of the SQL Server CDC in 2008, which became very popular and is still in use today.

The Concept of SQL Server Change Data Capture

SQL Server CDC captures and records changes made in the source database, such as “Insert”, “Update”, or “Delete”. These can be accessed by any user seamlessly, with all details available in an easy-to-understand relational format. CDC provides all the information required for capturing the changes to an intended target. The data for modified and changed rows is available in CDC.

The changes made are stored in tables and are reflected in the structure of the tracked source tables. For data security, access to the table-valued functions of the changes is strictly controlled, thereby ensuring their safety.

One of the best examples of the SQL Server CDC technology is the ETL (Extract, Transform, and Load) application. In this instance, all data that has changed in the source tables of SQL is moved incrementally to a data warehouse or data mart by an ETL application.

The changes that are made in the database rows by SQL Server CDC are recognized by the columns of metadata present in the structure of the replicated tables.   

Once a task has been completed by SQL Server Change Data Capture, all the work that has taken place and the logged tables can be tracked and monitored through the new audit tables.  The source of the changes in Change Data Capture is reflected in the transaction logs of the SQL Server.