Change Data Capture CDC and AWS DMS Replication

 

Change Data Capture (CDC) is the process that identifies and captures the changes made to the last refreshed data or metadata with periodicity fixed at minutes or even seconds. The changes made are entered in a separate data repository by specific software. Similar to batch loads, CDC ensures that the replication software copies one source to several targets.



AWS DMS is a cloud-based service that facilitates easy migration of relational databases, data warehouses, NoSQL databases through AWS DMS CDC. It can also be used for migrating data to the AWS cloud or on-premises setup or a combination of both. Since AWS DMS is a component of the AWS cloud, it has all the features of AWS cloud services like cost efficiency, speed to market, security, and flexibility.

An AWS DMS CDC can be created for capturing current changes to the source data during the replication process. Regardless of whether the work is a CDC-only task or a full-load one the migration process has tables only from the source. 

While reading concurrent changes from the source database, AWS DMS CDC uses engine-based API actions from the source transaction logs. It is done in the following way.    

·        For Microsoft SQL Server, AWS DMS uses MS-Replication or MS-CDC to enter information to the SQL Server transaction log.

·        For Oracle, AWS DMS CDC uses either the Oracle LogMiner API or the binary reader API to track ongoing changes. AWS DMS reads ongoing changes from the online or archived redo logs based on the SCN (System Change Number).

·        For MySQL, AWS DMS reads changes from the row-based binary logs and loads to the target.

This is how CDC in AWS DMS works.  

 

 

 

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