Asynch CDC: Delete old archived redo logs

October 9, 2008

The following steps need to be taken to be able to delete archived redo logs that are no longer required by the CDC capture process:
1. Determine the new first_scn for your capture process

As per Oracle documentation: This query “determines a new first_scn value that is greater than the original first_scn value and less than or equal to the applied_scn and required_checkpoint_scn”. So the new first_scn is the lower value of applied_scn and required_checkpoint_scn.
2. Raise the first_scn for the change source:

3. Identify which redo log files can be deleted:

4. Write a script to delete or archive obsolete archived redo logs based on the results of the query in step 3.