Oracle Database 21c the new release of the longtime activity leading RDBMS is currently useful in the Oracle Cloud where it can be deployed as a Virtual Machine DB System (for clusters and one entreaty) or a Bare Metal DB System (one entreaty). Its also useful in the Always Free Autonomous Database Service with limited storage and CPU space. It will be useful more broadly later this year including on-premises.
While Oracle Database 20c was scheduled for release in 2020 that release was cancelled owing of the COVID-19 pandemic and its effect on customer IT departments. All of the features planned for 20c were rolled into 21c.
There are separate notable points to be made almost Oracle Database 21c. It can obey as a transactional analysis or enterprise database and tune itself for its usage. It supports relational time series graph spatial text OLAP XML and JSON data. It has in-database training of machine learning models that includes AutoML and that training can take gain of the extra CPUs in storage obeyrs on Exadata hardware. Speaking of Exadata hardware Oracle Database 21c takes full gain of its Intel Optane persistent remembrance and the Autonomous Database supports automatic index creation which is also useful for Oracle Databases running on Exadata in the cloud or on-premises.
Oracle claims high accomplishance for all of its converged data types even compared over databases specialized for JSON documents or graphs. The hard benchmark numbers for Oracle Database 21c are not yet useful however.