1. Oracle GoldenGate Classic Architecture Documentation
  2. Prepare
  3. Prepare Your Database for Oracle GoldenGate Classic Architecture
  4. SQL Server
  5. Requirements Summary for Capture and Delivery of Databases in an Always On Availability Group
  6. Operational Requirements and Considerations

Operational Requirements and Considerations

  • When an instance is no longer the primary instance but has the SQL Server CDC Capture job installed, the job ceases to run after some time and does not attempt to restart. Upon failover back to that instance, the job does not automatically start, so it must be manually started.

  • If secondary replica databases are not in sync with the primary replica database, the CDC capture job will not advance in the log, and therefore no records will be captured by an Extract, until such time that the primary and secondary replicas are synchronized. See this article from Microsoft for more details:

    https://docs.microsoft.com/en-us/sql/database-engine/availability-groups/windows/replicate-track-change-data-capture-always-on-availability?view=sql-server-2017

    Note:

    When capturing from either a primary or a secondary replica in an Always On Availability Group, it is important to understand that the capture process must only read hardened transactions from the log, and that there be no potential for data loss between any replica database that Oracle GoldenGate is or will capture from.

  • When running an Extract from a middle tier Windows or Linux server, set the middle tier server's date, time, and time zone to the same as that of the primary replica.

  • Upon failover from a primary to a secondary replica, reinstall the Oracle GoldenGate CDC Cleanup job on the new primary by re-running the ogg_cdc_cleanup_setup.bat file with the createJob option.

  • If Extract is configured to capture from a readable secondary replica, but not configured with read-only routing, the SQL Server CDC Capture job must be created against the secondary replica prior to starting the Extract, as the Extract will check if the job exists. To create the SQL Server CDC Capture job, any potential secondary that will have an Extract connected to it, must at some point be set to a writable Primary database and then follow the steps above, under supplemental logging, to manually add the SQL Server CDC Capture job.

  • If uninstalling Oracle GoldenGate and disabling Change Data Capture on a database that is part of an Always On availability group, follow the extra steps provided in Disabling Change Data Capture.