1. Oracle GoldenGate Microservices Documentation
  2. Prepare
  3. Prepare Databases
  4. SQL Server
  5. Transaction Log Settings and Requirements
  6. CDC Capture Method Operational Considerations
  7. Details of the Oracle GoldenGate CDC Cleanup Process

Details of the Oracle GoldenGate CDC Cleanup Process

The Oracle GoldenGate Purge Change Data task is required for a CDC Extract by default, since Extract defaults to TRANLOGOPTIONS MANAGECDCCLEANUP.

There should only be one purge task for each database enabled for CDC Capture, and you must create the task using the steps mentioned in the Preparing the Source Database for Oracle GoldenGate Capture section of this document.

Modifying the Oracle GoldenGate Purge Change Data Task

The default purge task frequency schedule, and data retention period for the Oracle GoldenGate Purge Change Data task is to run every 10 minutes, with a data retention policy of 3 days or 1 hour, depending on the version of Oracle GoldenGate installed.

For customer specific requirements, it may be necessary to adjust the retention period (Keep Rule option) and the task run-time schedule (Purge Frequency option).

The Keep Rule option determines in hours or days, the amount of CDC staging data to keep in the source database. Depending on the version of Oracle GoldenGate installed, the default values are either 3 days or 1 hour. Lower CDC data retention periods reduce the amount of CDC staging data stored in the database but limit the ability for a user to reposition the Extract back to a time older than the data that exists in the staging tables. Typically, there would be no need to reposition an existing Extract back to an earlier point in time, so it is recommended to use the newer default setting of 1 hour unless there is a specific case that requires more staging data to remain in the database. Note that though if you change this value from a higher retention period to a very short retention period, the next time the task schedule runs, it could consume a lot of transaction log space and system overhead. So it is recommended to slowly decrease the Keep Rule value over time, until you reach the desired ending value.

The Purge Frequency represents how often the task runs, with a default of every 10 minutes. It is recommended to keep the default value unless overhead from the purge task is impacting database performance during periods of high user activity.

To modify an existing Purge Change Data task, navigate to the Configuration from the menu on the left of the Administration Service, to open the Configuration page.
  1. Click Tasks from the Configuration page to open the Tasks page.
  2. Click Purge Change Data from the Tasks page.
  3. Click the Alter Task icon next to an existing task.
  4. Modify the values of Keep Rule and Purge Frequency options as required.
  5. Click Submit to save the changes.

Deleting the Oracle GoldenGate Purge Change Data Task

Deleting a Purge Change Data task for a database should only be done if there are no Extracts configured to capture against the specific database.

To delete an existing Purge Change Data task, navigate to the Configuration option from the menu on the left of the Administration Service, to open the Configuration page.
  1. Click Tasks from the Configuration page to open the Tasks page.
  2. Click Purge Change Data from the Tasks page.
  3. Click the Delete Task icon next to the task to be removed.