Review the list of prerequsites to upgrade an Exadata Cloud@Customer Oracle Database instance.

• The Exadata Cloud@Customer system software must use Oracle Linux 7 (OL7). See How to update the Exadata System Software (DomU) to 19 from 18 on the Exadata Cloud Service in OCI for instructions on manually updating the operating system.
• The Oracle Grid Infrastructure must be version 19c. If patches are available for your Grid Infrastructure, Oracle recommends applying them prior to performing a database upgrade.
• You must have an available Oracle Database Home that uses the two most recent versions of Oracle Database 19c available in Oracle Cloud Infrastructure. See Using the Console to Create Oracle Database Home on Exadata Cloud@Customer for information on creating a Database Home. You can use Oracle-published software images or a custom database software image based on your patching requirements to create Database Homes.
• You must ensure that all pluggable databases in the container database that is being upgraded can be opened. Pluggable databases that cannot be opened by the system during the upgrade can cause an upgrade failure.

See the Oracle Database documentation for your database's release version to learn more about these settings.

Before you upgrade the database, become familiar with the following procedures to prepare your database for upgrade.

• Database upgrades involve database downtime. Keep this in mind when scheduling your upgrade.
• Oracle recommends that you back up your database and test the new software version on a test system or a cloned version of your database before you upgrade a production database. See Creating an On-Demand Backup by Using the bkup_api Utility for information on creating an on-demand manual backup.
• Oracle recommends running an upgrade precheck operation for your database prior to attempting an upgrade so that you can discover any issues that need mitigation prior to the time you plan to perform the upgrade. The precheck operation does not affect database availability and can be performed at any time that is convenient for you.
• If your databases use Data Guard, you will need to disable or remove the Data Guard association prior to upgrading.
• An upgrade operation cannot take place while an automatic backup operation is underway. Before upgrading, Oracle recommends disabling automatic backups and performing a manual backup. See Creating an On-Demand Backup by Using the bkup_api Utility and Customizing the Automatic Backup Configuration for more information.
• After upgrading, you cannot use automatic backups taken prior to the upgrade to restore the database to an earlier point in time.
• If you are upgrading a database that uses version 11.2 software, the resulting version 19c database will be a non-container database (non-CDB).

Familiarize yourself with what the Database service does during the upgrade process.

• Executes an automatic precheck. This allows the system to identify issues needing mitigation and to stop the upgrade operation.
• Sets a guaranteed restore point, enabling it to perform a flashback in the event of an upgrade failure.
• Moves the database to a user-specified Oracle Database Home that uses the desired target software version.
• Runs the Database Upgrade Assistant (DBUA) software to perform the upgrade.

If your upgrade does not complete successfully, then you have the option of performing a rollback.

Details about the failure are displayed on the Database Details page in the Console, allowing you to analyze and resolve the issues causing the failure.

A rollback resets your database to the state prior to the upgrade. All changes to the database made during and after the upgrade will be lost. The rollback option is provided in a banner message displayed on the database details page of a database following an unsuccessful upgrade operation. See Using the Console to Roll Back a Failed Database Upgrade for more information.

After a successful upgrade, note the following:

• Check that automatic backups are enabled for the database if you disabled them prior to upgrading. See Customizing the Automatic Backup Configuration for more information.
• Edit the Oracle Database

  COMPATIBLE

  parameter to reflect the new Oracle Database software version. See What Is Oracle Database Compatibility? for more information.
• If your database uses a database_name.env file, ensure that the variables in the file have been updated to point to the 19c Database Home. These variables should be automatically updated during the upgrade process.
• If you are upgrading a non-container database to Oracle Database version 19c, you can convert the database to a pluggable database after converting. See How to Convert Non-CDB to PDB (Doc ID 2288024.1) for instructions on converting your database to a pluggable database.
• If your old Database Home is empty and will not be reused, you can remove it. See Using the Console to Delete an Oracle Database Home for more information.

Oracle recommends that you use the precheck action to ensure that your database has met the requirements for the upgrade operation.

• Using the Console to Run Oracle Database Upgrade Precheck or Perform Upgrade
  
• Using the Console to Roll Back a Failed Database Upgrade
  
• Using the Console to View the Upgrade History of a Database
  

Review the list of API calls to upgrade Oracle Databases.

For information about using the API and signing requests, see REST APIs and Security Credentials. For information about SDKs, see Software Development Kits and Command Line Interface.

For the complete list of APIs, see Database Service API.