Upgrading a Database

Perhaps your task is not to create a new database, but to upgrade an existing database. A database upgrade is necessary when Oracle DBA have an older database such as Oracle9i and need to upgrade it to the current release. Oracle provides a tool for upgrading an existing database, called the Database Upgrade Assistant (DBUA).

The Database Upgrade Assistant (DBUA) interactively steps Oracle DBA through the upgrade process and configures the database for the new Oracle Database 10g release. The Database Upgrade Assistant automates the upgrade process by performing all of the tasks normally performed manually.

The Database Upgrade Assistant makes appropriate recommendations for configuration options such as tablespaces and redo logs. Oracle DBA can then act on these recommendations. For example, the Database Upgrade Assistant recommends sizing information for the new SYSAUX tablespace, which is required in Oracle Database 10g. Before the Upgrade The Database Upgrade Assistant performs the following pre-upgrade steps: It checks for any invalid user accounts or roles It checks for any invalid datatypes It checks for any desupported character sets It checks for adequate resources, including rollback segments, tablespaces, and free disk space It optionally backs up all necessary files The Database Upgrade Assistant does not begin the upgrade until it completes all of the pre-upgrade steps.

During the Upgrade The Database Upgrade Assistant automatically modifies or creates new required tablespaces, invokes the appropriate upgrade scripts, archives the redo logs, and disables archiving during the upgrade phase. While the upgrade is running, the Database Upgrade Assistant shows the upgrade progress for each component.

The Database Upgrade Assistant writes detailed trace and log files and produces a complete HTML report for later reference. To enhance security, the Database Upgrade Assistant automatically locks new user accounts in the upgraded database. The Database Upgrade Assistant then proceeds to create new configuration files (parameter and listener files) in the new Oracle home.

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