Essential Prerequisites for a Successful Oracle Database 19c Upgrade
The key to a seamless Oracle Database 19c upgrade lies in meticulous preparation. Skipping a single prerequisite can lead to a failed upgrade, prolonged downtime, and significant recovery efforts. For experienced professionals, this stage is not just a checklist; it's a critical risk-mitigation process. This guide provides a comprehensive overview of the essential prerequisites that must be met before initiating an upgrade.
1. Source Database Health Check
Before you even consider the new 19c environment, you must ensure the health of your source database. An unhealthy database can carry forward problems that will complicate the upgrade.
Ensure the source database is on a supported release: Oracle Database 19c supports direct upgrades from 11.2.0.4, 12.1.0.2, 12.2.0.1, and 18c. If your database is an earlier version, you must perform an intermediate upgrade first.
Resolve any invalid objects: Prior to the upgrade, check for and compile any invalid objects. The presence of invalid objects can cause the upgrade script to fail. Run
utlrp.sqlto recompile all objects.Check for corrupted blocks: Run an RMAN check to identify any corrupted data blocks (
VALIDATE DATABASE). Corrupt blocks must be fixed before the upgrade begins.Gather dictionary statistics: Outdated statistics can cause the upgrade process to be slow or fail. Run
DBMS_STATS.GATHER_DICTIONARY_STATSto ensure the optimizer has accurate information.
2. Sizing and Storage Requirements
An upgrade requires additional space in several key areas. Insufficient disk space is a common cause of upgrade failures.
Temporary Tablespace: Ensure the temporary tablespace has sufficient free space, as the upgrade process may require a significant amount of temporary space for sorting and other operations.
SYSAUXandSYSTEMTablespaces: TheSYSTEMandSYSAUXtablespaces are critical for the database dictionary and other system components. The pre-upgrade utility will report the required space, but it's a best practice to ensure they are onAUTOEXTEND ONand have several gigabytes of free space.Disk Space for Oracle Home: The 19c software binaries require several gigabytes of disk space. This must be available on the target server. An out-of-place upgrade is highly recommended, which means you need a new, empty directory for the 19c Oracle Home.
3. Software and Patching
The software installation and patching strategy for 19c must be planned and executed carefully.
Install the Oracle 19c Software: Download and install the 19c binaries into a new, clean Oracle Home directory. Do not install into an existing Oracle Home.
Apply the Latest Release Updates (RUs): Oracle 19c is a long-term support release, and it is crucial to apply the latest Release Update (RU) and Release Update Revision (RUR) to the new 19c Oracle Home before you start the database upgrade. This ensures you're starting with the most stable and secure version.
Check for Critical Patch Updates (CPUs): Ensure any necessary security patches are also applied to the new 19c Oracle Home.
4. Configuration and Environment Setup
The environment where the upgrade takes place must be correctly configured to avoid common runtime errors.
Run the Pre-Upgrade Utility: This is the most important prerequisite step. The utility, located at
$ORACLE_HOME/rdbms/admin/preupgrade.jaron the 19c software, analyzes your source database and generates a detailed report. This report highlights mandatory and recommended actions, such as deprecated features to remove, invalid objects to fix, and tablespace sizing recommendations. The utility even generates scripts (preupgrade_fixups.sql) to automate many of these fixes.Secure a Full Backup: A full RMAN backup of the source database is non-negotiable. This serves as your fail-safe mechanism, allowing you to restore the database to its original state if the upgrade fails catastrophically. A guaranteed restore point is also a quick and effective method for a rollback.
Adjust Initialization Parameters: Review the 19c documentation for changes to initialization parameters. Some parameters from older releases may be deprecated or have different default values. The pre-upgrade utility will flag these.
Upgrade Client Software: If possible, plan to upgrade your client software (e.g., JDBC, ODBC drivers, Oracle Instant Client) to a 19c-compatible version. This preempts
ORA-28040authentication errors and other connectivity issues.
5. Multi-tenant Architecture (CDB/PDB) Consideration
If you are upgrading from a non-CDB architecture, you have a critical decision to make. While 19c still supports non-CDB, it's the last version to do so. The multitenant architecture (CDB/PDB) is the future.
Plan the transition: If you plan to move to a CDB/PDB architecture, you can do so as part of the upgrade using tools like DBUA or
dbca. The pre-upgrade utility will help you prepare for this transition.Understand the implications: Be aware that migrating to a multitenant architecture has implications for backup strategies, patching, and management. Plan for these changes in advance.
By treating these prerequisites not as a list of tasks but as a foundation for success, you can minimize risk and ensure your Oracle Database 19c upgrade is as smooth and predictable as possible.
Video Resources
This video demonstrates how to run and interpret the results of the pre-upgrade utility for a successful transition to Oracle 19c.
This video provides a practical guide on installing the Oracle 19c database software, which is the foundational step before the actual database upgrade.
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