The Technology and Functioning of SQL Server Change Data Capture

One of the major goals of data-driven organizations of today is to ensure data security and durability, both of which can be had through the Change Data Capture (CDC) technology. While making sure that that change data is stored in a way that does not affect its history, CDC also insulates data from possible breaches and hacking. Several solutions like complex queries, timestamps, and triggers had been tested in the past, but none had met with the success of the CDC.

Introduction of SQL Server Change Data Capture

In 2005, Microsoft launched the SQL Server Change Data Capture product. Its advanced features had “after update”, “after insert”, and “after deleting” capabilities. But this technology had no takers due to its complex nature and hence in 2008, a revised version of SQL Server Change Data Capture DC was launched that was a major improvement. It could capture and document historical data without any other activities or work.


The Technology Behind SQL Server Change Data Capture

The SQL Server Change Data Capture feature on the SQL Server makes changes such as insert, update, or delete with users able to access all details of the changes in a friendly relational format. CDC has every input required to capture all changes to a target environment including column information and metadata for modified and changed rows. These changes are stored in tables that reflect the structure of the columns of the tracked source tables. Access to the change data is strictly controlled through table-valued functions.

Why is the SQL Server Change Data Capture technology considered to be a leader in this field? Traditionally, all source tables in a data warehouse mirror the changes made to them and have to be refreshed periodically. This can be tedious and time-consuming affairs. On the other hand, the SQL Server Change Data Capture technology allows a smooth flow of changed data that is structured to help users apply it to various target platforms.

The Functioning of Microsoft SQL Server Change Data Capture

Changes that are made in tables by users are tracked and monitored by Change Data Capture which then stores them in relational tables that offer quick access for seamless retrieval of the data with T-SQL. In every case where CDC is applied to a database table, a mirror image is created of the tracked table. Further, the column structures of the replicated tables have additional columns of metadata that identify the changes made in the database rows.

The features and the structure of the source and the replicated tables are the same. Once a specific SQL Server Change Data Capture activity is completed the new audit tables track the logged tables and monitor all work done. The transaction logs of SQL Server CDC reflect the source of the changes in CDC.


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