Specifying CREATE DATABASE Statement Clauses

Protecting Your Database: Specifying Passwords for Users SYS and SYSTEM

The clauses of the CREATE DATABASE statement used for specifying the passwords for users SYS and SYSTEM are:

• USER SYS IDENTIFIED BY password

• USER SYSTEM IDENTIFIED BY password

If you omit these clauses, then these users are assigned the default passwords change_on_install and manager, respectively. A record is written to the alert log indicating that the default passwords were used. To protect your database, you must change these passwords using the ALTER USER statement immediately after database creation.

Oracle strongly recommends that you specify these clauses, even though they are optional in this release of Oracle Database. The default passwords are commonly known, and if you neglect to change them later, then you leave database vulnerable to attack by malicious users.

When choosing a password, keep in mind that beginning in Release 11g, passwords are case-sensitive. Also, there may be password formatting requirements for your database. See the section entitled "How Oracle Database Checks the Complexity of Passwords" in Oracle Database Security Guide for more information.

Creating a Locally Managed SYSTEM Tablespace

Specify the EXTENT MANAGEMENT LOCAL clause in the CREATE DATABASE statement to create a locally managed SYSTEM tablespace. The COMPATIBLE initialization parameter must be set to 10.0.0 or higher for this statement to be successful. If you do not specify the EXTENT MANAGEMENT LOCAL clause, then by default the database creates a dictionary-managed SYSTEM tablespace. Dictionary-managed tablespaces are deprecated.

If you create your database with a locally managed SYSTEM tablespace, and if you are not using Oracle Managed Files, then ensure that the following conditions are met:

• You specify the DEFAULT TEMPORARY TABLESPACE clause in the CREATE DATABASE statement.

• You include the UNDO TABLESPACE clause in the CREATE DATABASE statement.

About the SYSAUX Tablespace

The SYSAUX tablespace is always created at database creation. The SYSAUX tablespace serves as an auxiliary tablespace to the SYSTEM tablespace. Because it is the default tablespace for many Oracle Database features and products that previously required their own tablespaces, it reduces the number of tablespaces required by the database. It also reduces the load on the SYSTEM tablespace.

You can specify only datafile attributes for the SYSAUX tablespace, using the SYSAUX DATAFILE clause in the CREATE DATABASE statement. Mandatory attributes of the SYSAUX tablespace are set by Oracle Database and include:

• PERMANENT

• READ WRITE

• EXTENT MANAGMENT LOCAL

• SEGMENT SPACE MANAGMENT AUTO

You cannot alter these attributes with an ALTER TABLESPACE statement, and any attempt to do so will result in an error. You cannot drop or rename the SYSAUX tablespace.

The size of the SYSAUX tablespace is determined by the size of the database components that occupy SYSAUX. You can view a list of these components by querying the V$SYSAUX_OCCUPANTS view. Based on the initial sizes of these components, the SYSAUX tablespace must be at least 400 MB at the time of database creation. The space requirements of the SYSAUX tablespace will increase after the database is fully deployed, depending on the nature of its use and workload. For more information on how to manage the space consumption of the SYSAUX tablespace on an ongoing basis, see the "Managing the SYSAUX Tablespace".

If you include a DATAFILE clause for the SYSTEM tablespace, then you must specify the SYSAUX DATAFILE clause as well, or the CREATE DATABASE statement will fail. This requirement does not exist if the Oracle Managed Files feature is enabled (see "Specifying Oracle Managed Files at Database Creation").

The SYSAUX tablespace has the same security attributes as the SYSTEM tablespace.

Using Automatic Undo Management: Creating an Undo Tablespace

Automatic undo management uses an undo tablespace. To enable automatic undo management, set the UNDO_MANAGEMENT initialization parameter to AUTO in your initialization parameter file. Or, omit this parameter, and the database defaults to automatic undo management. In this mode, undo data is stored in an undo tablespace and is managed by Oracle Database. To define and name the undo tablespace yourself, you must include the UNDO TABLESPACE clause in the CREATE DATABASE statement at database creation time. If you omit this clause, and automatic undo management is enabled, then the database creates a default undo tablespace named SYS_UNDOTBS.

Creating a Default Permanent Tablespace

The DEFAULT TABLESPACE clause of the CREATE DATABASE statement specifies a default permanent tablespace for the database. Oracle Database assigns to this tablespace any non-SYSTEM users for whom you do not explicitly specify a different permanent tablespace. If you do not specify this clause, then the SYSTEM tablespace is the default permanent tablespace for non-SYSTEM users. Oracle strongly recommends that you create a default permanent tablespace.

Creating a Default Temporary Tablespace

The DEFAULT TEMPORARY TABLESPACE clause of the CREATE DATABASE statement creates a default temporary tablespace for the database. Oracle Database assigns this tablespace as the temporary tablespace for users who are not explicitly assigned a temporary tablespace.

You can explicitly assign a temporary tablespace or tablespace group to a user in the CREATE USER statement. However, if you do not do so, and if no default temporary tablespace has been specified for the database, then by default these users are assigned the SYSTEM tablespace as their temporary tablespace. It is not good practice to store temporary data in the SYSTEM tablespace, and it is cumbersome to assign every user a temporary tablespace individually. Therefore, Oracle recommends that you use the DEFAULT TEMPORARY TABLESPACE clause of CREATE DATABASE.

Specifying Oracle Managed Files at Database Creation

You can minimize the number of clauses and parameters that you specify in your CREATE DATABASE statement by using the Oracle Managed Files feature. You do this by specifying either a directory or Oracle Automatic Storage Management (Oracle ASM) disk group in which your files are created and managed by Oracle Database.

By including any of the initialization parameters DB_CREATE_FILE_DEST, DB_CREATE_ONLINE_LOG_DEST_n, or DB_RECOVERY_FILE_DEST in your initialization parameter file, you instruct Oracle Database to create and manage the underlying operating system files of your database. Oracle Database will automatically create and manage the operating system files for the following database structures, depending on which initialization parameters you specify and how you specify clauses in your CREATE DATABASE statement:

• Tablespaces and their datafiles

• Temporary tablespaces and their tempfiles

• Control files

• Redo log files

• Archived redo log files

• Flashback logs

• Block change tracking files

• RMAN backups

The following CREATE DATABASE statement shows briefly how the Oracle Managed Files feature works, assuming you have specified required initialization parameters:

CREATE DATABASE mynewdb
     USER SYS IDENTIFIED BY sys_password
     USER SYSTEM IDENTIFIED BY system_password
     EXTENT MANAGEMENT LOCAL
     UNDO TABLESPACE undotbs
     DEFAULT TEMPORARY TABLESPACE tempts1
     DEFAULT TABLESPACE users;

• The SYSTEM tablespace is created as a locally managed tablespace. Without the EXTENT MANAGEMENT LOCAL clause, the SYSTEM tablespace is created as dictionary managed, which is not recommended.

• No DATAFILE clause is specified, so the database creates an Oracle managed datafile for the SYSTEM tablespace.

• No LOGFILE clauses are included, so the database creates two Oracle managed redo log file groups.

• No SYSAUX DATAFILE is included, so the database creates an Oracle managed datafile for the SYSAUX tablespace.

• No DATAFILE subclause is specified for the UNDO TABLESPACE and DEFAULT TABLESPACE clauses, so the database creates an Oracle managed datafile for each of these tablespaces.

• No TEMPFILE subclause is specified for the DEFAULT TEMPORARY TABLESPACE clause, so the database creates an Oracle managed tempfile.

• If no CONTROL_FILES initialization parameter is specified in the initialization parameter file, then the database also creates an Oracle managed control file.

• If you are using a server parameter file (see "Managing Initialization Parameters Using a Server Parameter File"), then the database automatically sets the appropriate initialization parameters.

  See Also:

  • Chapter 17, "Using Oracle Managed Files", for information about the Oracle Managed Files feature and how to use it

  • Oracle Automatic Storage Management Administrator's Guide. for information about Automatic Storage Management

Supporting Bigfile Tablespaces During Database Creation

Oracle Database simplifies management of tablespaces and enables support for ultra-large databases by letting you create bigfile tablespaces. Bigfile tablespaces can contain only one file, but that file can have up to 4G blocks. The maximum number of datafiles in an Oracle Database is limited (usually to 64K files). Therefore, bigfile tablespaces can significantly enhance the storage capacity of an Oracle Database.

This section discusses the clauses of the CREATE DATABASE statement that let you include support for bigfile tablespaces.

CREATE DATABASE mynewdb
     USER SYS IDENTIFIED BY sys_password
     USER SYSTEM IDENTIFIED BY system_password
     SET DEFAULT BIGFILE TABLESPACE
     UNDO TABLESPACE undotbs
     DEFAULT TEMPORARY TABLESPACE tempts1;

ALTER DATABASE SET DEFAULT BIGFILE TABLESPACE;

SELECT PROPERTY_VALUE FROM DATABASE_PROPERTIES 
   WHERE PROPERTY_NAME = 'DEFAULT_TBS_TYPE';

CREATE DATABASE mynewdb
...
     BIGFILE UNDO TABLESPACE undotbs
        DATAFILE '/u01/oracle/oradata/mynewdb/undotbs01.dbf'
        SIZE 200M REUSE AUTOEXTEND ON MAXSIZE UNLIMITED;

CREATE DATABASE mynewdb
   SET DEFAULT BIGFILE TABLSPACE
...
     SMALLFILE DEFAULT TEMPORARY TABLESPACE tempts1
        TEMPFILE '/u01/oracle/oradata/mynewdb/temp01.dbf' 
        SIZE 20M REUSE
...

Specifying the Database Time Zone and Time Zone File

This section contains:

• Setting the Database Time Zone

• About the Database Time Zone Files

• Specifying the Database Time Zone File

SELECT * FROM V$TIMEZONE_NAMES;

Specifying FORCE LOGGING Mode

Some data definition language statements (such as CREATE TABLE) allow the NOLOGGING clause, which causes some database operations not to generate redo records in the database redo log. The NOLOGGING setting can speed up operations that can be easily recovered outside of the database recovery mechanisms, but it can negatively affect media recovery and standby databases.

Oracle Database lets you force the writing of redo records even when NOLOGGING has been specified in DDL statements. The database never generates redo records for temporary tablespaces and temporary segments, so forced logging has no affect for objects.

ALTER DATABASE NO FORCE LOGGING;