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Each Oracle release makes setup easier, but configuring naming resolution and authentication for Data Guard is still a challenging step. Editing files like tnsnames.ora and sqlnet.ora remains tedious, even with LDAP (recommended) or EZConnect. Automation tools like Puppet, Ansible, or cloud solutions help, but aren’t always in place.

For Data Guard, accurate naming resolution and authentication are crucial for successful broker connections. The DGConnectIdentifier property defines the main connection string.

Data Guard 26ai introduces the VALIDATE DGConnectIdentifier command, which tests connectivity, including credentials, from each instance to every member.

This proactive check helps you avoid errors like ORA-01017 and ORA-12514 during operations such as SWITCHOVER. Unlike earlier manual sqlplus checks, this command verifies connections using the actual database environment, offering true validation from the connecting database.

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Previously, the only supported way to view broker properties for members or configurations was by running the DGMGRL SHOW DATABASE or SHOW CONFIGURATION commands. These commands made it difficult to gather all properties for every member or to check for inconsistencies. Monitoring required manual parsing of the output, and there was no direct SQL option.

With Data Guard 26ai, you can now use the new V$DG_BROKER_PROPERTY view.

This lets you easily query all broker properties for each member or for the whole configuration, using familiar SQL tools.

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Data Guard 26ai introduces a new fixed view, V$DG_BROKER_ROLE_CHANGE, which tracks the last ten role transitions for a configuration. This view gathers information dynamically from the broker configuration file, logging both automatic and manual failovers (with reasons), switchovers, and each operation’s start and end times. We plan to add recovery point SCN details in a future Release Update, but this isn’t available yet.

This view makes it easy to see recent role changes without searching through alert logs. It also helps identify what was the primary database at any given moment. The view stores only the ten most recent role changes; to keep a longer history, you can copy its records into a regular table; for example, using a STARTUP trigger on the primary database.

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Until now, checking whether a database was ready to switch over or fail over meant running the VALIDATE DATABASE command through DGMGRL: there was no direct SQL alternative, and the VALIDATE DATABASE command isn’t available with other broker interfaces.

In Data Guard 26ai, the V$DG_BROKER_CONFIG view now includes two new columns: SWITCHOVER_READY and FAILOVER_READY. These columns, updated every minute by the Data Guard Broker’s health check, provide the status for switchover and failover readiness.

This means you can now monitor configuration topology, member status, and role change readiness directly with a SQL query, streamlining observability and monitoring through any SQL*Net client, without relying on DGMGRL.

For now, if either column shows “NO”, you still need DGMGRL for detailed diagnostics.

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Monitoring your Data Guard configuration is essential to ensure your database remains healthy. The Data Guard broker includes a VALIDATE DATABASE command which assesses the system’s health and determines its readiness for switchover or failover.
Up to 21c, this command checks technical readiness for these operations and confirms whether they are likely to succeed. However, some misconfigurations, such as disabled flashback logging or offline PDBs, might not cause immediate failures but still present risks of data loss or other operational issues.
For example, if flashback logging is disabled, a failover would require reinstating the former primary. If there are offline PDBs on the standby database, perhaps because the primary was cloned without copying over the data files, these PDBs would not be available after a failover. This situation could cause data loss. Other issues may not block a switchover, yet still lead to unwanted results.
Oracle Data Guard 26ai introduces strict database validation. This feature marks a database as not ready for switchover or failover if any advanced checks fail.

Strict validation checks include:

• Matching apply properties
• Matching transport properties
• All data files online
• All PDBs online
• Flashback logging and force logging enabled
• Properly configured and cleared log files
• No saved PDB states, which is important to avoid issues with Active Data Guard

To run all these checks at once, use:

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With release 26ai, generating AWR reports from Active Data Guard standby databases is now simple and direct, without extra configuration required.

Previously, starting in version 12c Release 2, you had to set up DB links and use the Remote Management Framework (RMF) with the DBMS_UMF package to let the primary database collect remote AWR snapshots from standby databases. This process, documented in MOS note 2409808.1 How to Generate AWRs in Active Data Guard Standby Databases (now KB140685), was complex and could lead to non-working state, especially after failovers.

Now, you can generate reports right on the standby database.
Under the hood, the procedure exports the snapshot to a dump file, transfers it internally to the primary host using Data Guard communication, and imports it on the primary database. All of this is transparent.

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With Oracle 12c’s introduction of Multitenant architecture, managing Data Guard setups became challenging when adding new databases to the primary CDB. In 12c Release 1, adding a pluggable database (PDB) would crash standby recovery. Release 2 improved this by offering the standbys=none option, letting you skip recovery for new PDBs. However, you then had to manually copy the new PDB to the standby and re-enable recovery. Otherwise, some PDBs ended up unprotected by Data Guard.

My colleague Sinan blogged about the pre-21c behavior here: https://database-heartbeat.com/2022/01/24/hot-clone-remote-pdb-in-data-guard/ 

With Oracle 21c (and in 26ai), creating or cloning a new PDB in the primary CDB now automatically copies it to the standby CDB and includes it in recovery: no interruptions or manual steps needed. Just ensure the standby CDB is open in read-only mode.

https://docs.oracle.com/en/database/oracle/oracle-database/26/sbydb/examples-of-using-oracle-data-guard.html#GUID-45590356-133B-47DC-AD19-3AA37348CD4D

This greatly simplifies working with the Multitenant architecture, which is now mandatory in 26ai.

Note: This feature works only for new or cloned PDBs, created locally or remotely. It does not support plugging in existing PDBs using a manifest file.

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Adding tempfiles in a Data Guard configuration has always been tricky. In 19c or lower, adding a tempfile doesn’t automatically create it on the standby database because tempfile operations (including creation) don’t generate redo. As a result, the standby doesn’t notice the change.

To work around this, you had to manually add the tempfile on the standby by opening the standby PDB in read-only mode—after stopping redo if you didn’t have an Active Data Guard license. Mohamadou explained this workaround in detail:
https://www.dbi-services.com/blog/dataguard-environment-and-database-tempfiles/

In release 26ai, the process is finally automatic—if you use Oracle-Managed Files (OMF) and set standby_file_management to auto. The system now writes a new redo marker whenever a tempfile is added, ensuring automatic creation on the standby.

My colleague Sinan also covered this topic here:
https://database-heartbeat.com/2023/09/26/temp-file-dg/

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Oracle AI Database Release Update 23.26.1 introduces tagging for broker configurations and their members. Tags (key-value pairs) let you add custom context to configuration objects like databases and far sync instances.

Currently, tags serve only for organization and classification, based on your business needs. For example, you might tag databases to track their lifecycle status, flag compliance requirements, or group them by location or department.

Use these commands to manage tags:

• EDIT CONFIGURATION SET TAG
• SHOW CONFIGURATION TAG
• EDIT DATABASE|FAR_SYNC|MEMBER SET TAG
• SHOW DATABASE|FAR_SYNC|MEMBER TAG

You can also view tags using the new fixed view V$DG_BROKER_TAG, or manage them with standard interfaces like the PL/SQL API and SQLcl.

Tag names beginning with “ORA” are reserved for possible future features, so avoid using that prefix. We may add new capabilities that rely on ORA-reserved tags.

Note: With 23.26.1, you have to explicitly activate this feature with:

This requirement will be removed in a future release update.

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Often, Data Guard setups use many standby databases, but only some should ever become primary. Others might serve as clone masters, reporting, testing, or staging only.
Previously, you couldn’t prevent an unwanted switchover or failover to these restricted standby databases. This was risky: customers must keep production workloads off test systems.
Oracle Database 26ai introduces a new broker property: PrimaryDatabaseCandidates. Set this to specify which databases can become primary. If you try to switch or fail over to a database not on the list, the broker blocks it.

You can update the candidate list at any time, so it’s flexible in emergencies.

Note: this only blocks broker-initiated switchovers and failovers. Manual SQL conversions bypass this check.

This enhancement has also been back-ported to 19.26.
My colleague Alex Blyth’s blogged about this property in the context of Exascale: https://alexblyth.net/2026/01/12/using-data-guard-broker-to-prevent-a-standby-database-becoming-the-primary/