A common user is a user that has the same identity in the root and in every existing and future PDB.

A common user can log in to the root and any container in which it has been granted CREATE SESSION privilege. The operations that a common user can perform depend on the privileges granted to the common user. Some administrative tasks, such as creating a PDB or unplugging a PDB, must be performed by a common user.

A CDB also supports local users. A local user is a user that exists in exactly one PDB.

Some database administrators manage an entire CDB, while others manage individual PDBs.

DBAs who manage an entire CDB connect to the CDB as common users, and manage attributes of the entire CDB and the root, as well as some attributes of PDBs. For example, these DBAs can create, unplug, plug in, and drop PDBs. They can also specify the temporary tablespace and the default tablespace for the root, and they can change the open mode of PDBs.

DBAs can also connect to a specific PDB as a local PDB administrator and then perform a subset of management tasks on the PDB that a DBA performs on a non-CDB. The subset includes tasks required for the PDB to support an application. For example, tasks can include management of tablespaces and schemas in a PDB, specification of storage parameters for that PDB, changing the open mode of the current PDB, and setting PDB-level initialization parameters.

A multitenant environment enables you to achieve several goals. You can complete general tasks to configure and use a multitenant environment.

These goals are described in "Benefits of the Multitenant Architecture". To do so, you must complete the following general tasks:

Task 1   Plan for the Multitenant Environment

Creating and configuring any database requires careful planning. A CDB requires special considerations. For example, consider the following factors when you plan for a CDB:

• The number of PDBs that will be plugged into each CDB

• The resources required to support the planned CDB

• Container management policies executed as an aggregate on the entire CDB or executed locally on individual PDBs

• Container database topology, which could consist of application containers with application PDBs or a CDB with PDBs, or a combination of both

See "Planning for CDB Creation" for detailed information about planning for a CDB.

Task 2   Create One or More CDBs

When you have completed the necessary planning, you can create one or more CDBs using either the Database Configuration Assistant (DBCA) or the CREATE DATABASE statement. In either case, you must specify the configuration details for each CDB.

See "About CDB Creation with DBCA" and "Creating a CDB" for detailed information about creating a CDB.

After a CDB is created, it consists of the root and PDB$SEED, as shown in Figure 3-1. The CDB root contains only Oracle maintained objects and data structures, and PDB$SEED is a generic seed database for cloning purposes.

Figure 3-1 A Newly Created CDB

Description of "Figure 3-1 A Newly Created CDB"

Task 3   Optionally, Create Application Containers

An application container is an optional component of a CDB that consists of an application root and the application PDBs associated with it. An application container stores data for one or more applications.

The following graphic shows a CDB with one empty application container.

Figure 3-2 An Application Container

Description of "Figure 3-2 An Application Container"

See "Overview of Applications in an Application Container".

Task 4   Create, Plug In, and Unplug PDBs

PDBs contain user data. After creating a CDB, you can create PDBs, plug unplugged PDBs into it, and unplug PDBs from it whenever necessary. You can unplug a PDB from a CDB and plug this PDB into a different CDB. You might move a PDB from one CDB to another if, for example, you want to move the workload for the PDB from one server to another.

See "Creating and Removing PDBs and Application Containers" for information about creating PDBs, plugging in PDBs, and unplugging PDBs.

Figure 3-3 shows a CDB with several PDBs.

Figure 3-3 A CDB with PDBs

Description of "Figure 3-3 A CDB with PDBs"

Figure 3-4 shows a CDB with PDBs, application containers, and application PDBs.

Figure 3-4 A CDB with PDBs, Application Containers, and Application PDBs

Description of "Figure 3-4 A CDB with PDBs, Application Containers, and Application PDBs"

Task 5   Administer and Monitor the CDB and Application Containers

Administering and monitoring a CDB involves managing the entire CDB, the root, and some attributes of PDBs. Some management tasks are the same for CDBs and non-CDBs, and some are different.

Administering and monitoring an application container is similar to administering and monitoring a CDB, but your actions only affect the application root and the application PDBs that are part of the application container.

See "After Creating a CDB" for descriptions of tasks that are similar and tasks that are different. Also, see "Administering a CDB" and "Monitoring CDBs and PDBs".

You can use Oracle Resource Manager to allocate and manage resources among PDBs hosted in a CDB, and you can use it to allocate and manage resource use among user processes within a PDB. See "Using Oracle Resource Manager for PDBs".

You can also use Oracle Scheduler to schedule jobs in a CDB and in individual PDBs. See "Using Oracle Scheduler with a CDB".

Task 6   Administer and Monitor PDBs and Application PDBs

Administering and monitoring a PDB or an application PDB is similar to administering and monitoring a non-CDB, but there are some differences. See "Administering PDBs" and "Monitoring CDBs and PDBs".

You can use various tools to configure and administer a multitenant environment.