Oracle 23ai & 26ai: Structural Changes Every DBA Needs to Know

 

The evolution from Oracle 19c to the latest 23ai and 26ai releases isn’t just about new AI features; it’s a fundamental shift in how the database is structured and managed. For DBAs, this means unlearning some old habits and embracing a more automated, secure, and streamlined architecture.

Here is a breakdown of the most impactful structural changes you’ll encounter.

Data Dictionary & Ownership: Strengthening the Core

Oracle is tightening the reins on internal object management to boost security and performance.

LogMiner Move: In a move toward better kernel control, LogMiner objects have migrated from the SYSTEM schema to SYS. This reduces the risk of accidental modification and aligns with "least privilege" principles.

Component Cleanup: During the upgrade process, Oracle now standardizes Spatial components under the MDSYS schema. Notably, older, legacy multimedia components are being stripped out to reduce the database footprint.

JSON Duality: For those managing JSON-relational duality views, remember that the _id column is now mandatory as the document identifier.

Modernizing Storage & Installation

The way we install and provision space has shifted toward modern hardware capabilities.

Bigfile by Default: New databases now default to BIGFILE tablespaces for SYSTEM, SYSAUX, and USER tablespaces. This simplifies management by allowing a single data file to grow into the terabyte range, reducing the number of files a DBA has to track.

Read-Only Oracle Homes: From Oracle Database 18c/19c onwards, the read-only Oracle home architecture has become the standard for simplifying patching and upgrades. By separating read-only software binaries ($ORACLE_HOME) from read-write configuration and log files ($ORACLE_BASE_CONFIG, $ORACLE_BASE_HOME), you can patch or upgrade in-place or out-of-place with less risk and easier management.

Multitenant Independence

Oracle continues to make Pluggable Databases (PDBs) feel like independent instances. One of the most requested features is finally here:

PDB-Specific Time Zones: SYSDATE and SYSTIMESTAMP can now follow the PDB’s specific time zone rather than inheriting the host's time. This is a game-changer for global applications consolidated on a single Container Database (CDB). This functionality is enabled from 26ai by setting the initialization parameter TIME_AT_DBTIMEZONE to TRUE for a PDB.

Security: Out with the Old

Legacy protocols are no longer just "discouraged" they are gone. To maintain compliance with modern standards like FIPS, Oracle has removed support for:

Deprecated Encryption: 3DES, TLS 1.0, and TLS 1.1 are gone/disabled.

In Oracle AI Database 26ai and future updates to 19c (19.32+), 3DES is disabled when operating in FIPS 140-3 mode.

Legacy Verifiers: Older password verifiers have been purged.

Oracle is strengthening security by moving away from legacy authentication methods. Oracle 26ai has deprecated older algorithms, and the minimum security strength has been elevated.

The New Standard: Only AES and modern, high-strength encryption levels are supported.

 FIPS 140-3 requires the use of approved algorithms, which primarily means AES (128, 192, 256) for encryption and SHA-2/SHA-3 for hashing.

Automation-First Upgrades

The manual "run-a-script-and-pray" days are ending.

AutoUpgrade is King: AutoUpgrade is now the primary, recommended method for moving to 23ai/26ai. It now includes REST APIs, making it easier to plug into your CI/CD pipelines.

Smarter Patching: Beginning with Oracle Database 26ai (and likely backported/available in RU 23.26.0.0), datapatch has been enhanced to automatically terminate sessions that block it from updating SQL/PLSQL objects, acting as a "kill-switch" to prevent maintenance window overruns.

SQL & Metadata Evolution

Small changes in SQL can have a big impact on your existing automation.

The Boolean Arrival: Oracle finally supports the BOOLEAN data type natively in SQL and JSON functions.

Version Parsing: The VERSION_FULL format has changed. If you have shell scripts or PL/SQL blocks that parse version strings (e.g., 19.0.0.0), you must update them to handle the new 23ai/26ai format to avoid logic errors.