Description:-

The multitenant option introduced in Oracle Database 12c allows a single container database (CDB) to host multiple separate pluggable databases (PDB). DBMS_PDB package permits to generate an XML metadata file from a non-CDB 12c database, Its like a unplug a Pluggable database. This is the article which will guide step-by-step Converting Non CDB to CDB in Oracle Database 12c Release.

Step 1: Check the database its properly up and running. shutdown the non-CDB and start it in read-only mode.

Non Container Database Name : NONCDB

Container database Name     : ORA_CDB

Non Container Database (Noncdb)

[oracle@localhost ~]$ . ora12c.env

[oracle@localhost ~]$ sqlplus / as sysdba

SQL*Plus: Release 12.2.0.1.0 Production on Thu Jan 21 14:45:36 2021

Copyright (c) 1982, 2016, Oracle.  All rights reserved.

Connected to:

Oracle Database 12c Enterprise Edition Release 12.2.0.1.0 – 64bit Production

SQL> select name,open_mode from v$database;

NAME   OPEN_MODE

NONCDB   READ WRITE

SQL> SELECT name, open_mode FROM v$pdbs;
no rows selected

Container database Name (Ora_cdb)

[oracle@localhost ~]$ . oracdb.env

[oracle@localhost ~]$ sqlplus / as sysdba

SQL*Plus: Release 12.2.0.1.0 Production on Thu Jan 21 14:56:55 2021

Copyright (c) 1982, 2016, Oracle.  All rights reserved.

Connected to an idle instance.

SQL> startup

ORACLE instance started.
Total System Global Area 1258291200 bytes
Fixed Size     8792296 bytes
Variable Size   872417048 bytes
Database Buffers   369098752 bytes
Redo Buffers     7983104 bytes
Database mounted.
Database opened.

SQL> select name,open_mode from v$database;

NAME   OPEN_MODE

ORA_CDB   READ WRITE

SQL> col name for a20

SQL> select name, open_mode FROM v$pdbs;

NAME      OPEN_MODE

PDB$SEED      READ ONLY

CDB                READ WRITE

[oracle@localhost ~]$ ps -ef | grep pmon

Step 2: Shutdown the non-CDB database and start it in read-only mode.

SQL> shutdown immediate ;

Database closed.
Database dismounted.
ORACLE instance shut down.

SQL> startup mount

ORACLE instance started.
Total System Global Area 1258291200 bytes
Fixed Size     8620224 bytes
Variable Size   872417088 bytes
Database Buffers   369098752 bytes
Redo Buffers     8155136 bytes
Database mounted.

SQL> alter database open read only;

Database altered.

Step 3: Create the XML file needed for cdb conversion. the non-cdb database using the DBMS_PDB_DESCRIBE procedure  creates an XML file in the same way that the unplug operation does for a PDB. 

 SQL> BEGIN
DBMS_PDB.DESCRIBE(
pdb_descr_file => ‘/tmp/noncdb.xml’);
END;
/

Step 4:Shutdown the NON-CDB database ( Noncdb).

SQL> shutdown immediate ;

Database closed.
Database dismounted.
ORACLE instance shut down.
SQL>

Step 5: Open the cdb database (ORA_CDB)

[oracle@localhost Desktop]$ cd

[oracle@localhost ~]$ . oracdb.env

[oracle@localhost ~]$ sqlplus / as sysdba

SQL*Plus: Release 12.2.0.1.0 Production on Tue Jan 19 20:36:39 2021

Copyright (c) 1982, 2016, Oracle.  All rights reserved.

Connected to an idle instance.

SQL> startup

ORACLE instance started.
Total System Global Area 1258291200 bytes
Fixed Size     8792296 bytes
Variable Size   872417048 bytes
Database Buffers   369098752 bytes
Redo Buffers     7983104 bytes
Database mounted.
Database opened.

SQL>  select name,open_mode,cdb from v$database;

NAME   OPEN_MODE          CDB

ORA_CDB   READ WRITE        YES

Step 6: Check the compatibility of PDB in ( ORA_CDB).

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

Step 7: Check the violations of PDB in (ORA_CDB).

 SQL> select name,cause,type,message,status from PDB_PLUG_IN_VIOLATIONS where name=’NONCDB’;

Step 8: Create pluggable database in container db (ORA_CDB).

 SQL> create pluggable database pdb1 using ‘/tmp/noncdb.xml’ NOCOPY;

create pluggable database pdb1 using ‘/tmp/noncdb.xml’ NOCOPY

*ERROR at line 1:
ORA-27038: created file already exists
ORA-01119: error in creating database file

‘/u01/app/oracle/oradata/NONCDB/datafile/o1_mf_temp_j0lhxlpy_.tmp’

Note: As tempfile is already there, so mention tempfile reuse tag, to avoid this error.

SQL> create pluggable database pdb1 using ‘/tmp/noncdb.xml’ NOCOPY tempfile reuse;

Step 9: Switch to the PDB container and run the “$ORACLE_HOME/rdbms/admin/noncdb_to_pdb.sql” script to clean up the new PDB, removing any items that should not be present in a PDB.

SQL> ALTER SESSION SET CONTAINER=pdb1;

SQL> @$ORACLE_HOME/rdbms/admin/noncdb_to_pdb.sql

Step 10: Startup the PDB and check the open mode PDB.

SQL> alter Pluggable database pdb1 open;

SQL> SELECT name, open_mode FROM v$pdbs;

The non-cdb database has been converted to CDB now successfully.

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