19c → Oracle AI Database 26ai (23ai) upgrade: AutoUpgrade

Use this for a major release upgrade (19c → 26ai); for a quarterly RU within the same release use the "Applying an Oracle Database 19c Release Update (RU)" guide. Uses AutoUpgrade, the tool Oracle recommends: latest autoupgrade.jar, config file, analyze → fixups → deploy, an automatic fallback point with a guaranteed restore point, in-place upgrade of a 19c CDB or conversion of a non-CDB into a PDB in a 26ai CDB. Then time zone, statistics, the COMPATIBLE warning and the restore/rollback path. Separate paths for single instance, Oracle Restart and RAC (AutoUpgrade handles cluster_database and the srvctl registration itself).

Topology: 1 server, Oracle Restart or RAC (26ai home on all nodes)

Before you start

• Direct upgrade path: according to Oracle's 26ai Upgrade Guide, a direct upgrade to 26ai is supported only from 19c and 21c (older releases are upgraded to 19c first). The source 19c should be on the latest RU; the guide sets no minimum RU, but AutoUpgrade analyze reports missing patches/one-offs.
• On the source, COMPATIBLE is at least 19.0.0 (the lowest value 26ai accepts). If it is lower (11.2/12.x), it must first be raised on 19c; this cannot be undone and invalidates restore points.
• The 26ai software is installed under … (ZIP/gold image path) with the latest 26ai RU applied; Java in the home (…) is present.… On RAC the 26ai home must be installed at the same path on every node as a RAC (cluster) installation; this check runs on every node.…
• The target CDB … was created with dbca in the 26ai home and is open; the character set is compatible with the source (an AL32UTF8 CDB is recommended), db_create_file_dest is set… and there is free space equal to the source database size (copy)….
• The source is in ARCHIVELOG mode, the FRA is configured and has enough free space (for the flashback and archived logs generated during the upgrade; roughly 10–20% of the database size as additional space).
• A full RMAN backup taken immediately before the upgrade, with a tested restore, is available (the guide also includes it as a step).… For a non-CDB conversion without copying, this is the only fallback path.…
• The application has been tested with 26ai and the steps in this guide were rehearsed on a test database first; client drivers (JDBC/OCI) support 26ai.
• The maintenance window is approved; monitoring is in blackout; scheduled jobs and application connections will be stopped during the upgrade.
• The server can reach download.oracle.com (for autoupgrade.jar), or the latest jar will be copied manually.
• Grid Infrastructure is upgraded to 26ai (…): the database release cannot be higher than the Grid release. …Clusterware is at the same release and healthy on all nodes.…The Oracle Restart stack runs from the new Grid home.…
• The database is registered with Clusterware and points to the source home (Oracle home: …).
• The server operating system supports 26ai (Oracle Linux / RHEL 8 or 9). A 19c database on OL7/RHEL 7 cannot be upgraded to 26ai in place: upgrade the operating system first or move to a new server.

Phases of the guide

• Pre-checks — Check the source database · Check the target CDB · Download the latest autoupgrade.jar · Write the AutoUpgrade config file · Run analyze · Review the analyze report …
• Backup and fallback point — Take a full RMAN backup · Check FRA space
• Upgrade (deploy) — Stop the application · Start deploy · Monitor progress · Check the result
• Post-upgrade — Switch environment files to the new home… (…)… · Move the listener to the 26ai home · Verify the Clusterware registration · Check version, components, time zone and warnings · Make sure the PDBs stay open · Gather dictionary statistics …
• Rollback (only if needed) — Return to the restore point with AutoUpgrade restore · Verify the source database on 19c · Restore from backup · Verify the 19c dictionary and components