Convert a non-container database to a multitenant pluggable database

Originally published by TriCore: August 29, 2017

Oracle® version 12c offers multitenant database options for host multiple pluggable databases (PDB) with a single container database (CDB). Sometimes, you need to convert a non-CDB database into a CDB pluggable database. This blog describes methods that you can use to convert a non-CDB database into a CDB database.

Test case setup

This test scenario starts with a non-CDB database instance, noncdb12c, that is running on the machine ABC123.xyz.com. The task is to create a CDB database, cdb12c, on the same machine. You need to make sure you have enough disk space to hold the converted CDB database.

Host server: ABC123.xyz.com

Non-CDB database: noncdb12c

Oracle version: 12.1.0.2

The following image shows the test scenario:

Convert a non-container database to a multitenant pluggable database

Conversion tests

Use the steps in this section to convert the non-CDB database to a CDB database.

Step 1: Perform a clean shutdown

Perform the following steps to cleanly shut down the non-CDB database:

Set the environment to noncdb12c.
Execute the following command:
```
  sqlplus / as sysdba
```
Run the following code at the SQL prompt:
```
  shutdown immediate
```

Step 2: Open the database as read-only

After you have cleanly shutdown the database, perform the following steps to start the database in mount exclusive mode and open the database in read-only mode:

Set the environment to noncdb12c.
Execute the following command:
```
  sqlplus / as sysdba
```

Run the following code at the SQL prompt:

  startup mount exclusive

  alter database open read only;

Step 3: Generate a PDB manifest file

Perform the following steps to generate a PDB manifest file from the non-CDB:

Set the environment to noncdb12c.
Execute the following command:
```
  sqlplus / as sysdba
```

Run the following code at the SQL prompt:

  exec dbms_pdb.describe (pdb_descr_file=>'/tmp/noncdb12c_manifest_file.xml');

Step 4: Shutdown the non-CDB

Perform the following steps after Step 3 completes to shut down the non-CDB file.

Set the environment to noncdb12c.
Execute the following command:
```
  sqlplus / as sysdba
```
Run the following code at the SQL prompt:
```
  shutdown immediate
```

Step 5: Start the CDB

If the CDB is not already running, perform the following steps to start it and to check compatibility:

Set the environment to cdb12c.
Execute the following command:
```
  sqlplus / as sysdba
```

Run the following code at the SQL prompt:

  startup
  SET SERVEROUTPUT ON;
   DECLARE
   Compatible CONSTANT VARCHAR2(3) :=CASE  DBMS_PDB.CHECK_PLUG_COMPATIBILITY
   (pdb_descr_file => '/tmp/noncdb12c_manifest_file.xml')
   WHEN TRUE THEN 'YES'
   ELSE 'NO'
   END;
   BEGIN
      DBMS_OUTPUT.PUT_LINE(compatible);
   END;
   /

Step 6: Check for errors

After the CDB database startup completes, perform the following steps to check for errors in the PDB_PLUG_IN_VIOLATIONS view:

Set the environment to cdb12c.
Execute the following command:
```
  sqlplus / as sysdba
```

Run the following code at the SQL prompt:

  startup
  SELECT name, cause, type, message, status FROM PDB_PLUG_IN_VIOLATIONS
  WHERE name='NONCDB12C';

Note: If there are any errors, fix them before proceeding.

Step 7: Connect to the CDB and plug into the PDB

Perform the following steps to connect to the CDB and plug into the PDDB12C database by using the non-CDB manifest file:

Set the environment to cdb12c.
Execute the following command:
```
  sqlplus / as sysdba
```

Run the following code at the SQL prompt:

  CREATE PLUGGABLE DATABASE pdb12c USING '/tmp/noncdb12c_manifest_file.xml'
   COPY
   FILE_NAME_CONVERT = ('<Datafile_Location_for_noncdb>', 'Datafile_Location_for_pdb');

Note: The following options are supported, and you can choose one based on your environment:

COPY: The datafiles of the noncdb remain intact, and the noncdb is copied to create a PDB at the new location and keep the original datafiles intact at the original location. This means that a noncdb database is still operational after the creation of the PDB.
MOVE: The datafiles of the noncdb are moved to a new location to create a PDB. In this case, the noncdb database is not available after the PDB is created.
NOCOPY: The datafiles of the noncdb are used to create a PDB2, and it uses the same location as the noncdb. In this case, the noncdb database is not available after the PDB is created.

You can use the FILE_NAME_CONVERT parameter to specify the new location of the datafiles while using either the COPY or MOVE option.

Step 8: Run the conversion script

After step 7 completes successfully, perform the following steps to switch to the PDB container and run the conversion script, $ORACLE_HOME/rdbms/admin/noncdb_to_pdb.sql:

Set the environment to cdb12c.
Execute the following command:
```
  sqlplus / as sysdba
```

Run the following code at the SQL prompt:

  alter session set container=pdb12c
  @$ORACLE_HOME/rdbms/admin/noncdb_to_pdb.sql

Step 9: Start the PDB and verify the mode

Perform the following steps to start the PDB and verify that the mode is open:

Set the environment to cdb12c.
Execute the following command:
```
  sqlplus / as sysdba
```

Run the following code at the SQL prompt:

  alter pluggable database open;
  SELECT name, open_mode FROM v$pdbs;

Conclusion

When you convert a non-CDB database to a CDB pluggable database, you can choose from several options depending upon the size of the database.

If the database is very large, you might use the NOCOPY option. This minimizes the amount of extra space needed and reduces the time it takes to perform the conversion operation. The NOCOPY option is risky, however, because you don’t keep the original database files intact. Thus, if you need to restore the database to the previous state, you must restore the database using the backups taken before the conversion activity.

If database size is smaller, you should use the COPY option so that, if there are any issues, the fallback to the old non-CDB is straightforward because the original files are always intact.

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