You can start the Database Upgrade Assistant (DBUA) via the

dbua

command (in UNIX environments) or by selecting Database Upgrade Assistant from the Oracle Configuration and Migration Tools menu option (in Windows environments). If you are using a UNIX environment, you will need to enable an Xwindows display prior to starting DBUA.

When started, DBUA will display a Welcome screen. At the next screen, select the database you want to upgrade from the list of available databases. You can upgrade only one database at a time.

After you make your selection, the upgrade process begins. DBUA will perform pre-upgrade checks (such as for obsolete initialization parameters or files that are too small). DBUA will then create the SYSAUX tablespace, a standard tablespace in all Oracle 10g databases. You can override Oracle’s defaults for the location and size parameters for the datafiles used by the SYSAUX tablespace.

DBUA will then prompt you to recompile invalid PL/SQL objects following the upgrade. If you do not recompile these objects after the upgrade, the first user of these objects will be forced to wait while Oracle performs a run-time recompilation.

DBUA will then prompt you to back up the database as part of the upgrade process. If you have already backed up the database prior to starting DBUA, you may elect to skip this step. If you choose to have DBUA back up the database, it will shut down the database and perform an offline backup of the datafiles to the directory location you specify. DBUA will also create a batch file in that directory to automate the restoration of those files to their earlier locations.

The next step is to choose whether to enable Oracle Enterprise Manager (OEM) to manage the database. If you enable the Oracle Management Agent, the upgraded database will automatically be available via OEM.

You will then be asked to finalize the security configuration for the upgraded database. As with the database-creation process, you can specify passwords for each privileged account or you can set a single password to apply to all the OEM user accounts.

Finally, you will be prompted for details on the flash recovery area location (see Chapter 15), the archive log setting, and the network configuration. A final summary screen displays your choices for the upgrade, and the upgrade starts when you accept them. After the upgrade has completed, DBUA will display the Checking Upgrade Results screen, showing the steps performed, the related log files, and the status. The section of the screen titled Password Management allows you to manage the passwords and the locked/unlocked status of accounts in the upgraded database.

If you are not satisfied with the upgrade results, you can choose the Restore option. If you used DBUA to perform the backup, the restoration will be performed automatically; otherwise, you will need to perform the restoration manually.

When you exit DBUA after successfully upgrading the database, DBUA removes the old database’s entry in the network listener configuration file, inserts an entry for the upgraded database, and reloads the file.