Upgrading to Oracle Database 19c, 23ai, or beyond is not a single decision, but a series of carefully coordinated choices. As part of our 12 Days of Oracle 26ai series, we’re sharing a direct excerpt from the Getting to Oracle Database 19c or 23ai chapter of Upgrading Oracle Databases.
This chapter walks through the primary upgrade paths available to DBAs, helping teams move from planning into hands-on testing and execution. Once you understand your downtime constraints, hardware requirements, and architectural considerations, the next step is choosing the right upgrade method.
Below is a selected portion of the chapter.
In earlier chapters, we discussed how to plan for your Oracle database upgrade and evaluate high-level upgrade options. At this point, you should have a solid understanding of your possible upgrade paths, including hardware needs, operating system changes, multitenant considerations, and most importantly, how much downtime your applications can tolerate.
With those decisions in hand, it’s time to begin sandbox testing and technical validation. Let’s take a closer look at each upgrade method.
For in-place upgrades, your tool choice depends on your team’s expertise and the features currently in use within your database:
AutoUpgrade
Oracle’s recommended, Java-based command-line tool that performs pre-upgrade checks, resolves many common issues, and executes the upgrade process. AutoUpgrade can resume failed upgrades and run multiple upgrades in parallel.
Database Upgrade Assistant (DBUA)
A long-standing Java-based GUI tool that performs pre-upgrade checks and upgrades. DBUA can also run in silent mode using a response file.
Manual Upgrade
A fully manual process requiring strict adherence to Oracle documentation
and My Oracle Support notes, with all steps performed interactively via the command line.
Upgrade timelines vary widely. Factors include database size, retained audit and performance history, number of objects, and hardware capacity. Core metadata, Java components, and built-in PL/SQL are updated during the process, all of which affect duration.
Planning ahead by staging software, patches, and time zone updates is critical, especially for multi-stage upgrades.
Cross-platform upgrades combine two efforts: copying the database to a new platform and then performing an in-place upgrade. Oracle provides several tools for this process:
Data Pump for logical data or tablespace migration
RMAN for physical file-based migration
Data Guard for synchronized replication between systems
For environments requiring minimal downtime, Oracle offers real-time or rolling upgrade options using licensed technologies:
Active Data Guard, often using transient logical standby
GoldenGate, providing full logical replication across differing platforms
These approaches require parallel source and target systems running for extended periods, sometimes weeks or months, and add operational complexity. Larger systems increase the challenge of keeping environments synchronized throughout the process.
If you plan to adopt Oracle’s multitenant architecture, you can introduce CDB/PDB during the upgrade. Options include converting to a single PDB or plugging into an existing CDB. While powerful, this adds complexity and should not be attempted without prior multitenant experience, especially when diagnosing performance issues.
Ultimately, upgrade decisions should be driven by the applications the database supports. Some applications enforce specific upgrade paths or require unavoidable outages. Others may allow simpler migration approaches.
Understanding application constraints, user expectations, and acceptable downtime is essential to selecting the right upgrade strategy.
Carpe indicii! Seize the data.
This excerpt only scratches the surface of Oracle database upgrades. Upgrading Oracle Databases provides in-depth guidance on planning, execution, tooling, performance validation, and real-world upgrade scenarios.
Written by Oracle ACE Directors Sean Scott, Gary Gordhamer, and Charles Kim, the book is an essential resource for DBAs preparing for modern Oracle upgrades.
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