A Guide To SQL Server Change Data Capture (CDC)

 Let us start with the basics of SQL Server CDC (Change Data Capture). Its goal is to record all changes made in the data, like delete, update, or insert, after which, their details are provided to users in a simple relational format. The changes that are captured and noted in the source tables are replicated under column information in the target tables.

However, unlimited access is not given to the changes recorded by SQL Server CDC, as it is a matter of ensuring data safety and security. Permission to access the changes is strictly controlled by the table-valued function.

Functions of SQL Server Change Data Capture

The benefit of SQL Server CDC is that it automatically updates users with changes made to the database. These changes can be applied to specific tables or applications whenever needed. One example of the optimized use of SQL Server CDC is the Extract, Transform, and Load application. It extracts data from a source table, transforms it to match the data structure of the destination database, and finally, moves the processed data to a data warehouse or a data mart. 

All changes made by users in tables are tracked by SQL Server CDC. These are then stored in relational tables to be accessed and retrieved whenever required through T-SQL. A replicated image of the change table is automatically created whenever the Change Data Capture function is applied to a database table.  

The replicated tables created by SQL Server CDC have additional columns of metadata that monitor changes made in the database rows. This is the only difference between the source and the replicated tables, which are otherwise the same in all respects. This resemblance makes it easy for users to use the CDC function to monitor the logged tables and access the new audit tables.

In SQL Server CDC, all changes made in the tracked source tables are instantly entered in the log, and their details are linked to the change data section of the original source table. 


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