How to enable data validation for AWS DMS database migration task

A question that comes up is how to validate data migrated between two databases using  the AWS Data Migration Service (DMS)  . 

AWS DMS supports a validation process as part of the Database migration task set up . It is possible to view the data validation through the console , AWS CLI or the AWS DMS API. 

If you're using the AWS console - there is an "Enable validation"  configurable as  Create\Modify Database migration Task . 

You may find that you've enabled Validation - rerun the Database Migration Task and see this entry in the CloudWatch logs

2022-06-17T15:20:14 [VALIDATOR_EXT ]I: No primary/unique key found, skipping the validation for Table : myTable (table_partitioner.c:275)

The data validator won't work without a Primary Key on the source table. The DMS  database migration task will migrate the Primary Key - if it exists - to the target table during the migration process. The data validator utilises the Primary Key 

Go back and add a Primary Key to the source tables - rerun the load and this time the data validator will run as expected.  Once the task is completed - you can monitor the CloudWatch Logs .

You can also go into the Table Statistics section choose the table(s) and you should now see some extra information related to Validation