Oracle Multitenant New Features – Oracle Database 20c….

Continuing the series , this post is about the new features of Oracle Multitenant introduced in database 20c.

Namespace Integration with Database

Database Nest is an infrastructure that provides operating system resource isolation and management, file system isolation, and secure computing for CDBs and PDBs. This infrastructure enables a database instance to run in a protected, virtualized environment.

Sharing instance-level and operating system resources can lead to security and isolation constraints, especially in large-scale cloud deployments. Vulnerabilities can be external, such as compromised applications, unauthorized access of resources, and shared resources. An example of an internal vulnerability is a compromised Oracle process.

Database Nest isolates a database instance from other databases and applications running on the same host, and also isolates PDBs from each other and from the CDB. The feature is implemented as a Linux-specific package that provides hierarchical containers, called nests. A CDB resides within a single parent nest, while PDBs reside within the individual child nests created within the parent.

Linux processes in a PDB nest have their own process ID (PID) number spaces and cannot access PIDs in other nests. Process isolation provides a last level of defense in a security breach if a malicious user compromises a process.


MAX_IDLE_BLOCKER_TIME sets the number of minutes that a session holding needed resources can be idle before it is a candidate for termination.

MAX_IDLE_TIME sets limits for all idle sessions, whereas MAX_IDLE_BLOCKER_TIME sets limits only for idle sessions consuming resources. MAX_IDLE_TIME can be problematic for a connection pool because it may continually try to re-create the sessions terminated by this parameter.

Expanded Syntax for PDB Application Synchronization

The ALTER PLUGGABLE DATABASE APPLICATION … SYNC statement now accepts multiple application names and names to be excluded. For example, a single statement issued in an application PDB can synchronize app1 and app2, or synchronize all applications except app3.

The expanded syntax enables you to reduce the number of synchronization statements. Also, the database replays the statements in correct order. Assume that you upgrade ussales from v1 to v2, and then upgrade eusales from v1 to v2, and then upgrade ussales from v2 to v3. The statement ALTER PLUGGABLE DATABASE APPLICATION ussales, eusales SYNC replays the statements in sequence, upgrading ussales to v2, then eusales to v2, and then ussales to v3.

For more information, refer to Oracle Multitenant Guide.

Hope that helps.