Examine this list of possible steps: 1.Raise the compatibility level on both databases. 2.Restart SQL Apply on the upgraded logical standby database. 3. Start SQL Apply on the old primary database. 4. Perform a Switchover to the logical standby database. 5. Upgrade the logical standby database. 6. Upgrade the old primary database. Which is the minimum number of steps in the correct order, to perform a rolling release upgrade of a data guard environment using an existing logical standby database and to enable the new functionality? 

Answer options:

A. 5, 2, 4, 3, 6, 1
B. 1, 5, 2, 4, 6, 3
C. 5, 2, 4, 6, 3, 1
D. 4, 6, 5, 2, 3, 1
E. 5, 2, 4, 1

A

Execution: Execution of the rolling upgrade has five stages. Stage 1 (5): The DBMS_ROLLING.START_PLAN procedure starts the execution of the rolling upgrade. This converts the LGM database, the future primary database, to a logical standby and starts the SQL Apply process at the LGM. Stage 2 (2): You upgrade the database software at the databases that are part of the leading group. You also run the upgrade scripts at the LGM. After this is done, you must restart SQL Apply processes at the LGM database. Stage 3 (4): After the apply lag reaches a given threshold (set to 10 minutes by default, but can be configured during the specification stage), the DBMS_ROLLING.SWITCHOVER procedure proceeds with the switchover operation. When the switchover is complete, the LGM becomes the primary database. Stage 4 : The LGM is now the primary database running the new database software and the databases in the leading group are protecting it. The TGM is mounted and the databases in the trailing group are still running the older version of the database software. You must prepare the TGM and TGS databases for upgrade by upgrading the database software and re-mounting the databases on the higher version binaries. Stage 5 (3, 6): Execute the DBMS_ROLLING.FINISH_PLAN procedure at the current primary database (originally the LGM). It reinstates all the databases in the trailing group to become the standbys of the current primary database, and restarts the apply processes. The FINISH_PLAN procedure waits for all databases in the trailing group to be upgraded to the new release (although the database software for the trailing group databases was changed in Stage 4, the data dictionary of the trailing group databases, except for any logical standbys in the trailing group, are updated based on media recovery of the redo generated during the upgrade at the LGM database). Note: To upgrade the database software in an Oracle Data Guard configuration in a rolling fashion, you first designate a physical standby as the future primary database. Conceptually, the rolling upgrade process splits the Oracle Data Guard configuration into two groups: the leading group (LG) and the trailing group (TG). Databases in the leading group are upgraded first; hence the name leading group. The leading group contains the designated future primary database, and the physical standbys that you can configure to protect the designated future primary. The future primary is first converted into a logical standby database and then the new database software is installed on it and the upgrade process is run. Other standby databases in the leading group also must have their software upgraded at this point. References: https://docs.oracle.com/database/121/SBYDB/dbms_rolling_upgrades.htm