Asynch CDC: Delete old archived redo logs

Uli Bethke Oracle

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.

About the author

Uli Bethke LinkedIn Profile

Uli has 18 years’ hands on experience as a consultant, architect, and manager in the data industry. He frequently speaks at conferences. Uli has architected and delivered data warehouses in Europe, North America, and South East Asia. He is a traveler between the worlds of traditional data warehousing and big data technologies.

Uli is a regular contributor to blogs and books, holds an Oracle ACE award, and chairs the the Hadoop User Group Ireland. He is also a co-founder and VP of the Irish chapter of DAMA, a non for profit global data management organization. He has co-founded the Irish Oracle Big Data User Group.