Oracle 19C is now available on premise. There are lot of new features. One for the Data Guard Broker is that now we can dynamically change the fast-start failover target to a specified member in the list without disabling the fast-start failover.
I have tested this new feature and is describing this in this blog
I am using 3 servers with Oracle Linux
The Data Guard is already built and the broker is already configured
To enable the fast-start failover there are some requirements. Note that flashback database must be enabled for both databases.
First we put the the transport to SYNC for 3 databases

DGMGRL> edit database 'DB19C_SITE1' set property LogXptMode='SYNC';
Property "logxptmode" updated
DGMGRL> edit database 'DB19C_SITE2' set property LogXptMode='SYNC';
Property "logxptmode" updated
DGMGRL> edit database 'DB19C_SITE3' set property LogXptMode='SYNC';
Property "logxptmode" updated

After we change the protection to Maxavailability

DGMGRL>  EDIT CONFIGURATION SET PROTECTION MODE AS MaxAvailability;
Succeeded.

Then we set the fast-start failover target for both databases

DGMGRL> enable fast_start failover;
Enabled in Zero Data Loss Mode.

Below the status of the configuration. And we can see that DB19C_SITE2 is the target for the fast-start failover

DGMGRL> show configuration

Configuration - db19c

  Protection Mode: MaxAvailability
  Members:
  DB19C_SITE1 - Primary database
    DB19C_SITE2 - (*) Physical standby database
    DB19C_SITE3 - Physical standby database

Fast-Start Failover: Enabled in Zero Data Loss Mode

Configuration Status:
SUCCESS   (status updated 55 seconds ago)

DGMGRL>

The status of the observer will also show as the active target

DGMGRL> show observer

Configuration - db19c

  Primary:            DB19C_SITE1
  Active Target:      DB19C_SITE2

Observer "standserver2" - Master

  Host Name:                    standserver2
  Last Ping to Primary:         2 seconds ago
  Last Ping to Target:          4 seconds ago

DGMGRL>

For example let’s say we want to switchover to DB19C_SITE3

DGMGRL> switchover to 'DB19C_SITE3';
Performing switchover NOW, please wait...
Error: ORA-16655: specified standby database not the current fast-start failover target standby

Failed.
Unable to switchover, primary database is still "DB19C_SITE1"
DGMGRL>

As we can see we cannot because the first fast-start failover target is DB19C_SITE2. We have to change it to DB19C_SITE3
To dynamiccaly do this change , we use the command SET FAST_START FAILOVER TARGET.

DGMGRL> SET FAST_START FAILOVER TARGET TO 'DB19C_SITE3';
Waiting for Fast-Start Failover target to change to "DB19C_SITE3"...
Succeeded.
DGMGRL>

We can query the broker to verify the change

DGMGRL> show configuration

Configuration - db19c

  Protection Mode: MaxAvailability
  Members:
  DB19C_SITE1 - Primary database
    DB19C_SITE3 - (*) Physical standby database
    DB19C_SITE2 - Physical standby database

Fast-Start Failover: Enabled in Zero Data Loss Mode

Configuration Status:
SUCCESS   (status updated 22 seconds ago)

DGMGRL>

And then now I can switchover to DB19C_SITE3

DGMGRL> switchover to 'DB19C_SITE3';
Performing switchover NOW, please wait...
New primary database "DB19C_SITE3" is opening...
Operation requires start up of instance "DB19C" on database "DB19C_SITE1"
Starting instance "DB19C"...
Connected to an idle instance.
ORACLE instance started.
Connected to "DB19C_SITE1"
Database mounted.
Database opened.
Connected to "DB19C_SITE1"
Switchover succeeded, new primary is "DB19C_SITE3"
DGMGRL>

And the new status of the configuration

DGMGRL> show configuration

Configuration - db19c

  Protection Mode: MaxAvailability
  Members:
  DB19C_SITE3 - Primary database
    DB19C_SITE1 - (*) Physical standby database
    DB19C_SITE2 - Physical standby database

Fast-Start Failover: Enabled in Zero Data Loss Mode

Configuration Status:
SUCCESS   (status updated 51 seconds ago)

DGMGRL>


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by
Mouhamadou Diaw