Oracle Multitenant Environment (四) Create One or More CDBs

Using the CREATE DATABASE Statement to Create a CDB

This section describes creating a CDB using the CREATE DATABASE SQL statement.

Note:

Oracle strongly recommends using the Database Configuration Assistant (DBCA) instead of the CREATE DATABASE SQL statement to create a CDB, because using DBCA is a more automated approach, and your CDB is ready to use when DBCA completes.

This section contains the following topics:

• About Creating a CDB with the CREATE DATABASE Statement

• Creating a CDB with the CREATE DATABASE Statement

About Creating a CDB with the CREATE DATABASE Statement

Creating a CDB using the CREATE DATABASE SQL statement is very similar to creating a non-CDB. This section describes additional requirements for creating a CDB.

Using the CREATE DATABASE SQL statement is a more manual approach to creating a CDB than using DBCA. One advantage of using this statement over using DBCA is that you can create CDBs from within scripts.

When you create a CDB using the CREATE DATABASE SQL statement, you must enable PDBs and specify the names and locations of the root's files and the seed's files.

This section contains the following topics:

• About Enabling PDBs

• About the Names and Locations of the Root's Files and the Seed's Files

• About the Attributes of the Seed's Data Files

See Also:

Oracle Database Concepts for information about a CDB's files

About Enabling PDBs

To create a CDB, the CREATE DATABASE statement must include the ENABLE PLUGGABLE DATABASE clause. When this clause is included, the statement creates a CDB with the root and the seed.

When the ENABLE PLUGGABLE DATABASE clause is not included in the CREATE DATABASE statement, the newly created database is a non-CDB. The statement does not create the root and the seed, and the non-CDB can never contain PDBs.

About the Names and Locations of the Root's Files and the Seed's Files

The CREATE DATABASE statement uses the root's files (such as data files) to generate the names of the seed's files. You must specify the names and locations of the root's files and the seed's files. After the CREATE DATABASE statement completes successfully, you can use the seed and its files to create new PDBs. The seed cannot be modified after it is created.

You must specify the names and locations of the seed's files in one of the following ways:

1. The SEED FILE_NAME_CONVERT Clause

2. Oracle Managed Files

3. The PDB_FILE_NAME_CONVERT Initialization Parameter

If you use more than one of these methods, then the CREATE DATABASE statement uses one method in the order of precedence of the previous list. For example, if you use all of the methods, then the CREATE DATABASE statement only uses the specifications in the SEED FILE_NAME_CONVERT clause.

The SEED FILE_NAME_CONVERT Clause

The SEED FILE_NAME_CONVERT clause of the CREATE DATABASE statement specifies how to generate the names of the seed's files using the names of root's files.

You can use this clause to specify one of the following options:

• One or more file name patterns and replacement file name patterns, in the following form:

  'string1' , 'string2' , 'string3' , 'string4' , ...
  

  The string2 file name pattern replaces the string1 file name pattern, and the string4 file name pattern replaces the string3 file name pattern. You can use as many pairs of file name pattern and replacement file name pattern strings as required.

  If you specify an odd number of strings (the last string has no corresponding replacement string), then an error is returned. Do not specify more than one pattern/replace string that matches a single file name or directory.

  File name patterns cannot match files or directories managed by Oracle Managed Files.

• NONE when no file names should be converted. Omitting the SEED FILE_NAME_CONVERT clause is the same as specifying NONE.

Example 37-1 SEED FILE_NAME_CONVERT Clause

This SEED FILE_NAME_CONVERT clause generates file names for the seed's files in the /oracle/pdbseed directory using file names in the /oracle/dbs directory.

SEED
FILE_NAME_CONVERT = ('/oracle/dbs/', '/oracle/pdbseed/')

 

Oracle Managed Files

When Oracle Managed Files is enabled, it can determine the names and locations of the seed's files.

The PDB_FILE_NAME_CONVERT Initialization Parameter

The PDB_FILE_NAME_CONVERT initialization parameter can specify the names and locations of the seed's files. To use this technique, ensure that thePDB_FILE_NAME_CONVERT initialization parameter is included in the initialization parameter file when you create the CDB.

File name patterns specified in this initialization parameter cannot match files or directories managed by Oracle Managed Files.

About the Attributes of the Seed's Data Files

The seed can be used as a template to create new PDBs. The attributes of the data files for the root's SYSTEM and SYSAUX tablespaces might not be suitable for the seed. In this case, you can specify different attributes for the seed's data files by using the tablespace_datafile clauses. Use these clauses to specify attributes for all data files comprising the SYSTEM and SYSAUX tablespaces in the seed. The values inherited from the root are used for any attributes whose values have not been provided.

The syntax of the tablespace_datafile clauses is the same as the syntax for a data file specification, excluding the name and location of the data file and the REUSE attribute. You can use the tablespace_datafile clauses with any of the methods for specifying the names and locations of the seed's data files described in "About the Names and Locations of the Root's Files and the Seed's Files".

The tablespace_datafile clauses do not specify the names and locations of the seed's data files. Instead, they specifies attributes of SYSTEM and SYSAUXdata files in the seed that differ from those in the root. If SIZE is not specified in the tablespace_datafile clause for a tablespace, then data file size for the tablespace is set to a predetermined fraction of the size of a corresponding root data file.

Example 37-2 Using the tablespace_datafile Clauses

Assume the following CREATE DATABASE clauses specify the names, locations, and attributes of the data files that comprise the SYSTEM and SYSAUXtablespaces in the root.

DATAFILE '/u01/app/oracle/oradata/newcdb/system01.dbf' SIZE 325M REUSE
SYSAUX DATAFILE '/u01/app/oracle/oradata/newcdb/sysaux01.dbf' SIZE 325M REUSE

You can use the following tablespace_datafile clauses to specify different attributes for these data files:

SEED
SYSTEM DATAFILES SIZE 125M AUTOEXTEND ON NEXT 10M MAXSIZE UNLIMITED
SYSAUX DATAFILES SIZE 100M

In this example, the data files for the seed's SYSTEM and SYSAUX tablespaces inherit the REUSE attribute from the root's data files. However, the following attributes of the seed's data files differ from the root's:

• The data file for the SYSTEM tablespace is 125 MB for the seed and 325 MB for the root.

• AUTOEXTEND is enabled for the seed's SYSTEM data file, and it is disabled by default for the root's SYSTEM data file.

• The data file for the SYSAUX tablespace is 100 MB for the seed and 325 MB for the root.

 

Creating a CDB with the CREATE DATABASE Statement

When you use the CREATE DATABASE statement to create a CDB, you must complete additional actions before you have an operational CDB. These actions include building views on the data dictionary tables and installing standard PL/SQL packages in the root. You perform these actions by running the supplied catcdb.sql script.

The examples in the following steps create a CDB named newcdb.

To create a CDB with the CREATE DATABASE statement: 

1. Complete steps 1 - 8 in "Creating a Database with the CREATE DATABASE Statement".

   To create a CDB, the ENABLE_PLUGGABLE_DATABASE initialization parameter must be set to TRUE.

   In a CDB, the DB_NAME initialization parameter specifies the name of the root. Also, it is common practice to set the SID to the name of the root. The maximum number of characters for this name is 30. For more information, see the discussion of the DB_NAME initialization parameter in Oracle Database Reference.

2. Use the CREATE DATABASE statement to create a new CDB.

   The following examples illustrate using the CREATE DATABASE statement to create a new CDB:

   • Example 1: Creating a CDB Without Using Oracle Managed Files

   Example 1: Creating a CDB Without Using Oracle Managed Files

   The following statement creates a CDB named newcdb. This name must agree with the DB_NAME parameter in the initialization parameter file. This example assumes the following:

   • The initialization parameter file specifies the number and location of control files with the CONTROL_FILES parameter.

   • The directory /u01/app/oracle/oradata/newcdb exists.

   • The directory /u01/app/oracle/oradata/pdbseed exists.

   • The directories /u01/logs/my and /u02/logs/my exist.

   This example includes the ENABLE PLUGGABLE DATABASE clause to create a CDB with the root and the seed. This example also includes the SEEDFILE_NAME_CONVERT clause to specify the names and locations of the seed's files. This example also includes tablespace_datafile clauses that specify attributes of the seed's data files for the SYSTEM and SYSAUX tablespaces that differ from the root's.

   CREATE DATABASE newcdb
     USER SYS IDENTIFIED BY sys_password
     USER SYSTEM IDENTIFIED BY system_password
     LOGFILE GROUP 1 ('/u01/logs/my/redo01a.log','/u02/logs/my/redo01b.log') 
                SIZE 100M BLOCKSIZE 512,
             GROUP 2 ('/u01/logs/my/redo02a.log','/u02/logs/my/redo02b.log') 
                SIZE 100M BLOCKSIZE 512,
             GROUP 3 ('/u01/logs/my/redo03a.log','/u02/logs/my/redo03b.log') 
                SIZE 100M BLOCKSIZE 512
     MAXLOGHISTORY 1
     MAXLOGFILES 16
     MAXLOGMEMBERS 3
     MAXDATAFILES 1024
     CHARACTER SET AL32UTF8
     NATIONAL CHARACTER SET AL16UTF16
     EXTENT MANAGEMENT LOCAL
     DATAFILE '/u01/app/oracle/oradata/newcdb/system01.dbf'
       SIZE 700M REUSE AUTOEXTEND ON NEXT 10240K MAXSIZE UNLIMITED
     SYSAUX DATAFILE '/u01/app/oracle/oradata/newcdb/sysaux01.dbf'
       SIZE 550M REUSE AUTOEXTEND ON NEXT 10240K MAXSIZE UNLIMITED
     DEFAULT TABLESPACE deftbs
        DATAFILE '/u01/app/oracle/oradata/newcdb/deftbs01.dbf'
        SIZE 500M REUSE AUTOEXTEND ON MAXSIZE UNLIMITED
     DEFAULT TEMPORARY TABLESPACE tempts1
        TEMPFILE '/u01/app/oracle/oradata/newcdb/temp01.dbf'
        SIZE 20M REUSE AUTOEXTEND ON NEXT 640K MAXSIZE UNLIMITED
     UNDO TABLESPACE undotbs1
        DATAFILE '/u01/app/oracle/oradata/newcdb/undotbs01.dbf'
        SIZE 200M REUSE AUTOEXTEND ON NEXT 5120K MAXSIZE UNLIMITED
     ENABLE PLUGGABLE DATABASE
       SEED
       FILE_NAME_CONVERT = ('/u01/app/oracle/oradata/newcdb/', 
                            '/u01/app/oracle/oradata/pdbseed/')
       SYSTEM DATAFILES SIZE 125M AUTOEXTEND ON NEXT 10M MAXSIZE UNLIMITED
       SYSAUX DATAFILES SIZE 100M
     USER_DATA TABLESPACE usertbs
       DATAFILE '/u01/app/oracle/oradata/pdbseed/usertbs01.dbf'
       SIZE 200M REUSE AUTOEXTEND ON MAXSIZE UNLIMITED;
   

   A CDB is created with the following characteristics:

   • The CDB is named newcdb. Its global database name is newcdb.us.example.com, where the domain portion (us.example.com) is taken from the initialization parameter file. 

   • Three control files are created as specified by the CONTROL_FILES initialization parameter, which was set before CDB creation in the initialization parameter file. See "Sample Initialization Parameter File" and "Specifying Control Files".

   • The passwords for user accounts SYS and SYSTEM are set to the values that you specified. The passwords are case-sensitive. The two clauses that specify the passwords for SYS and SYSTEM are not mandatory in this release of Oracle Database. However, if you specify either clause, then you must specify both clauses. For further information about the use of these clauses, see "Protecting Your Database: Specifying Passwords for Users SYS and SYSTEM".

   • The new CDB has three online redo log file groups, each with two members, as specified in the LOGFILE clause. MAXLOGFILES, MAXLOGMEMBERS, and MAXLOGHISTORY define limits for the redo log. See "Choosing the Number of Redo Log Files". The block size for the redo logs is set to 512 bytes, the same size as physical sectors on disk. The BLOCKSIZE clause is optional if block size is to be the same as physical sector size (the default). Typical sector size and thus typical block size is 512. Permissible values for BLOCKSIZE are 512, 1024, and 4096. For newer disks with a 4K sector size, optionally specify BLOCKSIZE as 4096. See "Planning the Block Size of Redo Log Files" for more information.

   • MAXDATAFILES specifies the maximum number of data files that can be open in the CDB. This number affects the initial sizing of the control file.

     Note:

     You can set several limits during CDB creation. Some of these limits are limited by and affected by operating system limits. For example, if you set MAXDATAFILES, then Oracle Database allocates enough space in the control file to store MAXDATAFILES filenames, even if the CDB has only one data file initially. However, because the maximum control file size is limited and operating system dependent, you might not be able to set all CREATE DATABASE parameters at their theoretical maximums.

     For more information about setting limits during CDB creation, see the Oracle Database SQL Language Referenceand your operating system–specific Oracle documentation.

   • The AL32UTF8 character set is used to store data in this CDB.

   • The AL16UTF16 character set is specified as the NATIONAL CHARACTER SET used to store data in columns specifically defined as NCHAR, NCLOB, or NVARCHAR2.

   • The SYSTEM tablespace, consisting of the operating system file /u01/app/oracle/oradata/newcdb/system01.dbf, is created as specified by the DATAFILE clause. If a file with that name already exists, then it is overwritten.

   • The SYSTEM tablespace is created as a locally managed tablespace. See "Creating a Locally Managed SYSTEM Tablespace".

   • A SYSAUX tablespace is created, consisting of the operating system file /u01/app/oracle/oradata/newcdb/sysaux01.dbf as specified in theSYSAUX DATAFILE clause. See "About the SYSAUX Tablespace".

   • The DEFAULT TABLESPACE clause creates and names a default permanent tablespace for this CDB.

   • The DEFAULT TEMPORARY TABLESPACE clause creates and names a default temporary tablespace for this CDB. See "Creating a Default Temporary Tablespace".

   • The UNDO TABLESPACE clause creates and names an undo tablespace that is used to store undo data for this CDB. In a CDB, an undo tablespace is required to manage the undo data, and the UNDO_MANAGEMENT initialization parameter must be set to AUTO. If you omit this parameter, then it defaults to AUTO. See "Using Automatic Undo Management: Creating an Undo Tablespace".

   • Redo log files will not initially be archived, because the ARCHIVELOG clause is not specified in this CREATE DATABASE statement. This is customary during CDB creation. You can later use an ALTER DATABASE statement to switch to ARCHIVELOG mode. The initialization parameters in the initialization parameter file for newcdb relating to archiving are LOG_ARCHIVE_DEST_1 and LOG_ARCHIVE_FORMAT. See Chapter 12, "Managing Archived Redo Log Files".

   • The ENABLE PLUGGABLE DATABASE clause creates a CDB with the root and the seed.

   • SEED is required for the FILE_NAME_CONVERT clause and the tablespace_datafile clauses.

   • The FILE_NAME_CONVERT clause generates file names for the seed's files in the /u01/app/oracle/oradata/pdbseed directory using file names in the /u01/app/oracle/oradata/newcdb directory.

   • The SYSTEM DATAFILES clause specifies attributes of the seed's SYSTEM tablespace data file(s) that differ from the root's.

   • The SYSAUX DATAFILES clause specifies attributes of the seed's SYSAUX tablespace data file(s) that differ from the root's.

   • The USER_DATA TABLESPACE clause creates and names the seed's tablespace for storing user data and database options such as Oracle XML DB. PDBs created using the seed include this tablespace and its data file. The tablespace and data file specified in this clause are not used by the root.

   Note:

   • Ensure that all directories used in the CREATE DATABASE statement exist. The CREATE DATABASE statement does not create directories.

   • If you are not using Oracle Managed Files, then every tablespace clause must include a DATAFILE or TEMPFILEclause.

   • If CDB creation fails, then you can look at the alert log to determine the reason for the failure and to determine corrective actions. See "Viewing the Alert Log". If you receive an error message that contains a process number, then examine the trace file for that process. Look for the trace file that contains the process number in the trace file name. See "Finding Trace Files" for more information.

   • To resubmit the CREATE DATABASE statement after a failure, you must first shut down the instance and delete any files created by the previous CREATE DATABASE statement.