Dataguard

RAC-to-RAC DG 
- several standby instances can receive redo from the primary database
- only one standby instance can apply the redo stream generated by the primary instances
 


Rolling release upgrade (short, full - Doc 10.2)
perform a rolling upgrade ONLY using logical standby
S - on standby
P - on primary

1. S: ALTER DATABASE STOP LOGICAL STANDBY APPLY;

2. S: Upgrade

3. S: ALTER DATABASE START LOGICAL STANDBY APPLY IMMEDIATE; 

4. P: ALTER DATABASE COMMIT TO SWITCHOVER TO LOGICAL STANDBY; 

5. P: Upgrade

6. P: ALTER DATABASE START LOGICAL STANDBY APPLY IMMEDIATE NEW PRIMARY db_link_to_S;

7. P&S: Set compatibility

8. S: ALTER DATABASE COMMIT TO SWITCHOVER TO LOGICAL STANDBY;