Creating Application Containers

You can create application containers in several different ways, including using the PDB seed, cloning an existing PDB, and plugging in an unplugged PDB by using the CREATE PLUGGABLE DATABASE statement.

About Creating an Application Container

The CREATE PLUGGABLE DATABASE ... AS APPLICATION CONTAINER statement creates a new application container.

An application container consists of an application root and a collection of application PDBs that store data for one or more applications. The application PDBs are plugged into the application root, and you can optionally create an application seed for quick and easy creation of new application PDBs. The application PDBs and application root can share application common objects.

There are three types of application common objects:

Metadata-linked application common objects store the metadata for specific objects, such as tables, so that the containers that share the application common object have the same structure but different data.
Data-linked application common objects are defined once in the application root and shared as read-only objects in the context of hosted application PDBs.
Extended data-linked application common objects store shared data in the application root but also allow application PDBs to store data appended to that object. The appended data is local data that is unique to each application PDB.

You create an application container by including the AS APPLICATION CONTAINER clause in the CREATE PLUGGABLE DATABASE statement. You can use the following techniques to create an application container:

Using the PDB seed
Cloning an existing PDB
Relocating a PDB
Plugging in an unplugged PDB

To create an application container, the current container must be the CDB root and you must specify the AS APPLICATION CONTAINER clause in the CREATE PLUGGABLE DATABASE statement. You must create the application container using Oracle Managed Files.

Note:

An application container cannot be unplugged or dropped if any application PDBs belong to it.

Migrating Existing Applications to an Application Container

You can migrate an application to an application root by creating an application root using an existing PDB. You must complete additional tasks when you are migrating an existing application to an application container. The PDBs that you plug in must contain the application objects, including their data, and you must run procedures in the DBMS_PDB package to specify which objects are shared. Also, when application common users, roles, or profiles exist in the application root, you must run procedures in the DBMS_PDB package to specify that they are common.

After the application is migrated to the application root, you can create application PDBs in the application root, and create application PDBs using existing PDBs.

Preparing for Application Containers

Prerequisites must be met before creating an application container.

The CDB must exist.
The CDB must be in read/write mode.
The current user must be a common user whose current container is the CDB root.
The current user must have the CREATE PLUGGABLE DATABASE system privilege.
You must decide on a unique application container name for every application container. Every application container name must be unique with respect to all containers in a single CDB, and every application container name must be unique within the scope of all the CDBs whose database instances are reached through a specific listener.

The application container name is used to distinguish an application container from other containers in the CDB. Application container names follow the same rules as service names, which includes being case-insensitive.
You must create the containing using Oracle Managed Files.
If you are creating an application container in an Oracle Data Guard configuration with a physical standby database, then additional tasks must be completed before creating an application container.
If you are migrating an existing application to an application container using installation scripts, then the scripts must be available to run.
If you are migrating an existing application to an application container using a PDB, then it must be possible to clone the PDB to the application root or plug in the PDB into the application root.

Creating an Application Container

You can create an application container using the CREATE PLUGGABLE DATABASE statement with the AS APPLICATION CONTAINER clause.

Before creating an application container, complete the prerequisites described in "Preparing for Application Containers".

In SQL*Plus, ensure that the current container is the CDB root.
Run the CREATE PLUGGABLE DATABASE statement, and include the AS APPLICATION CONTAINER clause. Specify other clauses when they are required.
After you create the application container, it is in mounted mode, and its status is NEW. You can view the open mode of an application container by querying the OPEN_MODE column in the V$PDBS view. You can view the status of an application container by querying the STATUS column of the CDB_PDBS or DBA_PDBS view.

A new default service is created for the application container. The service has the same name as the application container and can be used to access the application container. Oracle Net Services must be configured properly for clients to access this service.
Open the new application container in read/write mode.
You must open the new application container in read/write mode for Oracle Database to complete the integration of the new application container into the CDB. An error is returned if you attempt to open the application container in read-only mode. After the application container is opened in read/write mode, its status is NORMAL.
Back up the application container.
A application container cannot be recovered unless it is backed up.

Note:

If an error is returned during application container creation, then the application container being created might be in an UNUSABLE state. You can check an application container's state by querying the CDB_PDBS or DBA_PDBS view, and you can learn more about application container creation errors by checking the alert log. An unusable application container can only be dropped, and it must be dropped before an application container or PDB with the same name as the unusable application container can be created.
If you are migrating an existing application to the application container, then follow the instructions in "Migrating an Existing Application to an Application Container".

The application container is created with an application root. You can create application PDBs in the application container.

Example 14-2 Creating an Application Container Using the PDB seed

This example assumes the following factors:

Storage limits are not required for the application container. Therefore, the STORAGE clause is not required.
The application container does not require a default tablespace.
The PATH_PREFIX clause is not required.
The FILE_NAME_CONVERT clause and the CREATE_FILE_DEST clause are not required.

Either Oracle Managed Files is enabled for the CDB, or the PDB_FILE_NAME_CONVERT initialization parameter is set. The files associated with the PDB seed will be copied to a new location based on the Oracle Managed Files configuration or the initialization parameter setting.
There is no file with the same name as the new temp file that will be created in the target location. Therefore, the TEMPFILE REUSE clause is not required.
No predefined Oracle roles need to be granted to the PDB_DBA role.

The following statement creates the application container from the PDB seed:

CREATE PLUGGABLE DATABASE salesact AS APPLICATION CONTAINER 
  ADMIN USER salesadm IDENTIFIED BY password;

Example 14-3 Creating an Application Container by Cloning a Local PDB

This example assumes the following factors:

The PATH_PREFIX clause is not required.
The FILE_NAME_CONVERT clause is required to specify the target locations of the copied files. In this example, the files are copied from /disk1/oracle/pdb1/ to /disk2/oracle/hract/.

The CREATE_FILE_DEST clause is not used, and neither Oracle Managed Files nor the PDB_FILE_NAME_CONVERT initialization parameter is used to specify the target locations of the copied files.

To view the location of the data files for a PDB, run the query in "Example 15-34".
Storage limits must be enforced for the application root. Therefore, the STORAGE clause is required. Specifically, all tablespaces that belong to the application root must not exceed 2 gigabytes. This storage limit does not apply to the application PDBs that are plugged into the application root.
There is no file with the same name as the new temp file that will be created in the target location. Therefore, the TEMPFILE REUSE clause is not required.

Given the preceding factors, the following statement clones hract as an application container from pdb1:

CREATE PLUGGABLE DATABASE hract AS APPLICATION CONTAINER FROM pdb1 
  FILE_NAME_CONVERT = ('/disk1/oracle/pdb1/', '/disk2/oracle/hract/')
  STORAGE (MAXSIZE 2G);

Note:

If you are migrating an existing application to the new application container, then follow the instructions in "Migrating an Existing Application to an Application Container".

Example 14-4 Creating an Application Container by Plugging In an Unplugged PDB

This example assumes the following factors:

The new application container is not based on the same unplugged PDB that was used to create an existing PDB or application container in the CDB. Therefore, the AS CLONE clause is not required.
The PATH_PREFIX clause is not required.
The XML file does not accurately describe the current locations of the files. Therefore, the SOURCE_FILE_NAME_CONVERT clause or SOURCE_FILE_DIRECTORY clause is required. In this example, the XML file indicates that the files are in /disk1/oracle/payroll/, but the files are in /disk2/oracle/payroll/, and the SOURCE_FILE_NAME_CONVERT clause is used.
The files are in the correct location. Therefore, NOCOPY is included.
Storage limits must be enforced for the application container. Therefore, the STORAGE clause is required. Specifically, all tablespaces that belong to the application container must not exceed 2 gigabytes.
A file with the same name as the temp file specified in the XML file exists in the target location. Therefore, the TEMPFILE REUSE clause is required.

The following statement plugs in the PDB:

CREATE PLUGGABLE DATABASE payrollact AS APPLICATION CONTAINER 
  USING '/disk1/usr/payrollpdb.xml' 
  SOURCE_FILE_NAME_CONVERT = ('/disk1/oracle/payroll/', 
                              '/disk2/oracle/payroll/')
  NOCOPY
  STORAGE (MAXSIZE 2G)
  TEMPFILE REUSE;

Note:

If you are migrating an existing application to the new application container, then follow the instructions in "Migrating an Existing Application to an Application Container".

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