Oracle 21c New Features

Even though it’s not listed in the main documentation page, Oracle 21c documentation exists. I went to the New Features Guide and here is a compilation of some of the new features I find interesting.

Zero Down Time Timezone Upgrade

I wrote in the past about timezone (DST) patches (here and here). One important thing about this is that DST patch required “startup upgrade”, meaning it is not a RAC-rolling patch and standby databases have to be in MOUNT and not OPEN. With this feature not only that these patches are RAC-rolling patches and standby databases can be OPEN, they will be installed while the database is up and running. Very cool! Maybe they will even be part of RUs and RURs now?

New SQL SET Operators

Set operators are UNION, MINUS and INTERSECT. With 21c we have some new operators:

• EXCEPT – identical to MINUS
• EXCEPT ALL – takes into consideration ALL rows for the EXCEPT (or MINUS). For example, if one row source is “a,a,b” and the other one is “a,b” then the first one MINUS the second one will return no rows (because both a and b exist in the second set). But the first one EXCEPT ALL the second one will return “a” because only one “a” exists in the second set.
• INTERSECT ALL – INTERSECT returns all values that exist in both sets, but the result will contain each value once. INTERSECT ALL returns the value the number of times it appears on both sets.

Expressions in Initialization Parameters

Until now, initialization parameters could only have a specific value. Now, you can have the value as an expression based on a different initialization parameter, for example:

alter system set pga_aggregate_target='sga_target/4';

Data Pump Checksum

Data Pump can now add a checksum for the dump file (using the CHECKSUM=YES option). This can assure that the file was not changed or tempered with before trying to import it.

AutoUpgrade Automation for Data Guard and RAC

For Data Guard: when using AutoUpgrade to upgrade the database, it will automatically perform Data Guard operations (like disabling and enabling the broker, and deferring log file transport while the database is being upgraded).

For RAC: AutoUpgrade will use SRVCTL stop stop and start instances, handle different initialization parameters (such as CLUSTER_DATABASE), and restart services.

AutoUpgrade Converts Non-CDB to CDB

As Non-CDB architecture is not supported anymore, AutoUpgrade will take the necessary steps to convert the Non-CDB database to a CDB database.

Attention Log

This is a new log in XML or JSON format, and it will contain messages that require the DBA attention. So no more scanning the alert log for errors or messages, the attention log should contain these messages and only them.

SQL*Net Log Enhancement

Oracle added a new “connection identifier”. This identifier will appear in CMAN log, the listener log, and client and server logs. With this identifier exist in all logs, it will be much easier to troubleshoot an issue.

Read-Only Oracle Home Default

Oracle introduced Read-Only Oracle Home in 18c, in 21c it is now the default behavior.

Automatic Materialized Views

Oracle will now be able to create and maintain materialized views without user interaction.

PREPARE DATABASE FOR DATA GUARD

This is a new dgmgrl command. It gets details about the database (such as the unique name and size of the DB_RECOVERY_FILE_DEST parameter) and sets everything needed for the database to be ready for Data Guard configuration.

Summary

This is only the tip, there are so many more features that I didn’t write about. If you’re interested, go to the New Features Guide and take a look at all the good stuff that is coming soon to Oracle database.