FLASHBACK STANDBY LOG

Purpose

The ALTER SYSTEM FLASHBACK STANDBY LOG statement is used to truncate the logs of a standby tenant to a specified point. This statement is typically used after a failover to integrate the original primary tenant's standby tenant into the new primary tenant.

Limitations and considerations

• For V4.2.5, the log truncation feature is supported starting from V4.2.5 BP4.

• Before executing this statement, ensure that the current standby tenant has stopped log synchronization and its restore source is empty.

• The standby tenant to be truncated must not have any valid replicas on the offline machine.

• This statement can only be executed on a standby tenant, and the tenant's STATUS must be NORMAL, and SWITCHOVER_STATUS must be NORMAL or FLASHBACK_AND_STAY_STANDBY_STATUS.

• When the standby tenant's SWITCHOVER_STATUS is FLASHBACK_AND_STAY_STANDBY_STATUS, it cannot continue to synchronize logs or modify its restore source.

• When specifying the log truncation point, the specified point must be greater than or equal to the standby tenant's synchronization point.

• Executing this statement will automatically clear the tenant's service name (SERVICE_NAME).

Privilege requirements

This statement must be executed by the root user of the sys tenant (root@sys) or the administrator user of each tenant. Specifically:

• In MySQL mode, the default administrator user is root.
• In Oracle mode, the default administrator user is SYS.

Syntax

ALTER SYSTEM FLASHBACK STANDBY LOG TO SCN = flashback_log_scn [TENANT = 'tenant_name'];

Parameters

Examples

Assume the confirmed log truncation point is 4611686018427387903. Here is an example of truncating the logs of the standby tenant standby_tenant.

• The system tenant truncates the logs of the specified tenant standby_tenant to the specified point.

  obclient(root@sys)[(none)]> ALTER SYSTEM FLASHBACK STANDBY LOG TO SCN = 4611686018427387903 TENANT = standby_tenant;
  

• The standby tenant truncates its own logs to the specified point.

  obclient> ALTER SYSTEM FLASHBACK STANDBY LOG TO SCN = 4611686018427387903;
  

References

For more information on log truncation, see Failover.