Oracle DBA

In the journey toward resilient, high-availability database systems, Oracle continually evolves. With Oracle 19c, Data Guard gains a set of refined features that strengthen standby operations, simplify recovery, and improve manageability. In this post, we’ll explore the key new Data Guard features introduced in Oracle 19c and their operational impact.

1. Automatic Flashback of Standby Database

Oracle 19c introduces the capability to automatically flash back a physical standby to a point in time captured on the primary—without manual intervention.

• Restore points on the primary are automatically replicated to the standby as “replicated restore points.”
• Regardless of whether the original restore point on the primary was “guaranteed” or “normal,” the replicated version is always treated as a normal restore point on the standby.
• This simplifies operations during time-based recovery and makes standby flashback more consistent and automated.

2. Restore Point Replication from Primary to Standby

Closely related to the above, the replication of restore points ensures that the standby has the same recovery markers as the primary.
This helps in reducing manual effort during failover or recovery: you don’t need to separately create matching restore points on the standby after fostering them in primary.

3. Active Data Guard DML Redirection

One of the most powerful enhancements is DML redirection in an Active Data Guard standby.

• Applications can issue DML statements (e.g. UPDATE, DELETE) against the standby database transparently. The DML is redirected to the primary, executed there, and the redo generated is applied to the standby before the control returns to the client.
• This lets you offload read workloads to the standby while still allowing incidental writes, thereby boosting overall throughput and balancing load between primary and standby.
• Even DML inside PL/SQL blocks or transactions are eligible for this redirection.

4. Automatic Outage / Hang Recovery in Data Guard

In complex production environments, processes handling redo transport or gap resolution may hang due to network or I/O issues. Oracle 19c Data Guard includes internal logic to detect and recover from hanging processes.

• The system can terminate stuck processes, restoring normal flow of redo transport and gap resolution.
• Several initialization parameters are now available to tune wait times and thresholds, allowing DBAs to align behavior with network and disk characteristics in their environment.

5. Automatic Deletion of Flashback Logs

To help manage storage in fast recovery areas, Oracle 19c supports automatic cleanup of flashback logs that exceed retention parameters.

• This feature requires COMPATIBLE parameter to be set to 19.0.0 or higher.
• It ensures that flashback space usage remains bounded and predictable, avoiding unexpected storage exhaustion in recovery areas.

Operational Takeaways & Recommendations

• Enable restore point replication to simplify standby flashback and time-based recovery workflows.
• Leverage DML redirection in Active Data Guard to improve performance, offload writes, and increase utility of standby databases.
• Monitor for hung processes in redo transport and gap resolution paths, and fine-tune timeout parameters as needed.
• Review flashback retention policies and ensure automatic deletion is enabled (with compatible version) to avoid storage surprises.

Oracle 19c’s Data Guard enhancements reflect Oracle’s commitment to making high-availability, disaster recovery, and standby operations more robust, intelligent, and hands-free. For the DBA, these features reduce complexity, improve safety, and allow more advanced, balanced deployment architectures.