CREATE DATABASE

Caution: This statement prepares a database for initial use and erases any data currently in the specified files. Use this statement only when you understand its ramifications.

Note Regarding Security Enhancements: In this release of Oracle9i and in subsequent releases, several enhancements are being made to ensure the security of default database user accounts. Beginning with this release, during initial installation with the Oracle Database Configuration Assistant (DCBA), all default database user accounts except SYS, SYSTEM, SCOTT, DBSNMP, OUTLN, AURORA$JIS$UTILITY$, AURORA$ORB$UNAUTHENTICATED and OSE$HTTP$ADMIN will be locked and expired. To activate a locked account, the DBA must manually unlock it and reassign it a new password. In the next release of the database server, the DBCA will prompt for passwords for users SYS and SYSTEM during initial installation of the database rather than assigning default passwords to them. In addition, a CREATE DATABASE SQL statement issued manually will require you to specify passwords for these two users. Oracle9i will be the last major release to support the user SYSTEM as a default database user created during any type of installation or by the CREATE DATABASE SQL statement.

Purpose

Use the CREATE DATABASE statement to create a database, making it available for general use.

This statement erases all data in any specified datafiles that already exist in order to prepare them for initial database use. If you use the statement on an existing database, all data in the datafiles is lost.

After creating the database, this statement mounts it in either exclusive or parallel mode (depending on the value of the CLUSTER_DATABASE initialization parameter) and opens it, making it available for normal use. You can then create tablespaces and rollback segments for the database.

See Also: ALTER DATABASE for information on modifying a database Oracle9i Java Developer's Guide for information on creating an Oracle9i Java virtual machine CREATE ROLLBACK SEGMENT and CREATE TABLESPACE for information on creating rollback segments and tablespaces

Prerequisites

To create a database, you must have the SYSDBA system privilege.

If the REMOTE_LOGIN_PASSWORDFILE initialization parameter is set to EXCLUSIVE, Oracle returns an error when you attempt to re-create the database. To avoid this message, either set the parameter to SHARED, or re-create your password file before re-creating the database.

See Also: Oracle9i Database Reference for more information about the REMOTE_LOGIN_PASSWORDFILE parameter

Syntax

create_database::=

Text description of create_database

autoextend_clause::=

Text description of autoextend_clause

maxsize_clause::=

Text description of maxsize_clause

default_temp_tablespace::=

Text description of default_temp_tablespace

temp_tablespace_extent::=

Text description of temp_tablespace_extent

undo_tablespace_clause::=

Text description of undo_tablespace_clause

filespec: See filespec.

set_time_zone_clause::=

Text description of set_time_zone_clause

Keyword and Parameters

database

Specify the name of the database to be created. The name can be up to 8 bytes long. The database name can contain only ASCII characters. Oracle writes this name into the control file. If you subsequently issue an ALTER DATABASE statement that explicitly specifies a database name, Oracle verifies that name with the name in the control file.

Note: You cannot use special characters from European or Asian character sets in a database name. For example, characters with umlauts are not allowed.

If you omit the database name from a CREATE DATABASE statement, Oracle uses the name specified by the initialization parameter DB_NAME. If the DB_NAME initialization parameter has been set, and you specify a different name from the value of that parameter, Oracle returns an error.

See Also: "Schema Object Naming Guidelines" for additional rules to which database names should adhere

CONTROLFILE REUSE Clause

Specify CONTROLFILE REUSE to reuse existing control files identified by the initialization parameter CONTROL_FILES, thus ignoring and overwriting any information they currently contain. Normally you use this clause only when you are re-creating a database, rather than creating one for the first time. You cannot use this clause if you also specify a parameter value that requires that the control file be larger than the existing files. These parameters are MAXLOGFILES, MAXLOGMEMBERS, MAXLOGHISTORY, MAXDATAFILES, and MAXINSTANCES.

If you omit this clause and any of the files specified by CONTROL_FILES already exist, Oracle returns an error.

LOGFILE Clause

Specify one or more files to be used as redo log files. Each filespec specifies a redo log file group containing one or more redo log file members (copies). All redo log files specified in a CREATE DATABASE statement are added to redo log thread number 1.

See Also: filespec for the syntax of filespec

GROUP integer

Specify the number that identifies the redo log file group. The value of integer can range from 1 to the value of the MAXLOGFILES parameter. A database must have at least two redo log file groups. You cannot specify multiple redo log file groups having the same GROUP value. If you omit this parameter, Oracle generates its value automatically. You can examine the GROUP value for a redo log file group through the dynamic performance view V$LOG.

If you omit the LOGFILE clause:

• If either the DB_CREATE_ONLINE_LOG_DEST_n or DB_CREATE_FILE_DEST initialization parameter (or both) is set, then Oracle creates two Oracle-managed logfiles with system-generated names, 100 MB in size, in the default logfile directory specified in the DB_CREATE_ONLINE_LOG_DEST_n parameter, and if it is not set, then in the DB_CREATE_FILE_DEST parameter.

• If neither of these parameters is set, Oracle creates two redo log file groups. The names and sizes of the default files depend on your operating system.

MAXLOGFILES Clause

Specify the maximum number of redo log file groups that can ever be created for the database. Oracle uses this value to determine how much space in the control file to allocate for the names of redo log files. The default, minimum, and maximum values depend on your operating system.

MAXLOGMEMBERS Clause

Specify the maximum number of members, or copies, for a redo log file group. Oracle uses this value to determine how much space in the control file to allocate for the names of redo log files. The minimum value is 1. The maximum and default values depend on your operating system.

MAXLOGHISTORY Clause

This parameter is useful only if you are using Oracle in ARCHIVELOG mode with Real Application Clusters. Specify the maximum number of archived redo log files for automatic media recovery Real Application Clusters. Oracle uses this value to determine how much space in the control file to allocate for the names of archived redo log files. The minimum value is 0. The default value is a multiple of the MAXINSTANCES value and depends on your operating system. The maximum value is limited only by the maximum size of the control file.

MAXDATAFILES Clause

Specify the initial sizing of the datafiles section of the control file at CREATE DATABASE or CREATE CONTROLFILE time. An attempt to add a file whose number is greater than MAXDATAFILES, but less than or equal to DB_FILES, causes the Oracle control file to expand automatically so that the datafiles section can accommodate more files.

The number of datafiles accessible to your instance is also limited by the initialization parameter DB_FILES.

MAXINSTANCES Clause

Specify the maximum number of instances that can simultaneously have this database mounted and open. This value takes precedence over the value of initialization parameter INSTANCES. The minimum value is 1. The maximum and default values depend on your operating system.

ARCHIVELOG | NOARCHIVELOG

ARCHIVELOG

Specify ARCHIVELOG if you want the contents of a redo log file group to be archived before the group can be reused. This clause prepares for the possibility of media recovery.

NOARCHIVELOG

Specify NOARCHIVELOG if the contents of a redo log file group need not be archived before the group can be reused. This clause does not allow for the possibility of media recovery.

The default is NOARCHIVELOG mode. After creating the database, you can change between ARCHIVELOG mode and NOARCHIVELOG mode with the ALTER DATABASE statement.

CHARACTER SET Clause

Specify the character set the database uses to store data. The supported character sets and default value of this parameter depend on your operating system.

Restriction: You cannot specify the AL16UTF16 character set as the database character set.

See Also: Oracle9i Globalization Support Guide for more information about choosing a character set

NATIONAL CHARACTER SET Clause

Specify the national character set used to store data in columns specifically defined as NCHAR, NCLOB, or NVARCHAR2 (either AF16UTF16 or UTF8). The default is 'AL16UTF16'.

See Also: Oracle9i Globalization Support Guide for information on Unicode datatype support.

DATAFILE Clause

Specify one or more files to be used as datafiles. All these files become part of the SYSTEM tablespace.

If you omit this clause:

• If the DB_CREATE_FILE_DEST initialization parameter is set, Oracle creates a 100 MB Oracle-managed datafile with a system-generated name in the default file destination specified in the parameter.

• If the DB_CREATE_FILE_DEST initialization parameter is not set, Oracle creates one datafile whose name and size depend on your operating system.

  Note: Oracle recommends that the total initial space allocated for the SYSTEM tablespace be a minimum of 5 megabytes.

  See Also: filespec for syntax

autoextend_clause

Use the autoextend_clause to enable or disable the automatic extension of a new datafile or tempfile. If you do not specify this clause, these files are not automatically extended.

ON

Specify ON to enable autoextend.

OFF

Specify OFF to turn off autoextend if is turned on.

Note: When you turn off autoextend, the values of NEXT and MAXSIZE are set to zero. If you turn autoextend back on in a subsequent statement, you must reset these values.

NEXT

Use the NEXT clause to specify the size in bytes of the next increment of disk space to be allocated automatically when more extents are required. Use K or M to specify this size in kilobytes or megabytes. The default is the size of one data block.

MAXSIZE

Use the MAXSIZE clause to specify the maximum disk space allowed for automatic extension of the datafile.

UNLIMITED

Use the UNLIMITED clause if you do not want to limit the disk space that Oracle can allocate to the datafile or tempfile.

default_temp_tablespace

Specify this clause to create a default temporary tablespace for the database. Oracle will assign to this temporary tablespace any users for whom you do not specify a different temporary tablespace. If you do not specify this clause, the SYSTEM tablespace is the default temporary tablespace.

Note: On some operating systems, Oracle does not allocate space for the tempfile until the tempfile blocks are actually accessed. This delay in space allocation results in faster creation and resizing of tempfiles, but it requires that sufficient disk space is available when the tempfiles are later used. Please refer to your operating system documentation to determine whether Oracle allocates tempfile space in this way on your system.

Restrictions:

• You cannot specify the SYSTEM tablespace in this clause.

• The default temporary tablespace must have a standard block size.

The temp_tablespace_extent clause lets you specify how the tablespace is managed.

EXTENT MANAGEMENT LOCAL

This clause indicates that some part of the tablespace is set aside for a bitmap. All temporary tablespaces have locally managed extents, so this clause is optional.

UNIFORM integer

Specify the size of the extents of the temporary tablespace in bytes. All extents of temporary tablespaces are the same size (uniform). If you do not specify this clause, Oracle uses uniform extents of 1M.

SIZE integer

Specify in bytes the size of the tablespace extents. Use K or M to specify the size in kilobytes or megabytes.

If you do not specify SIZE, Oracle uses the default extent size of 1M.

See Also: Oracle9i Database Concepts for a discussion of locally managed tablespaces

undo_tablespace_clause

If you have opened the instance in Automatic Undo Management mode, you can specify the undo_tablespace_clause to create a tablespace to be used for undo data. If you want undo space management to be handled by way of rollback segments, omit this clause.

• If you specify this clause, Oracle creates an undo tablespace named tablespace, creates the specified datafiles as part of the undo tablespace, and assigns this tablespace as the undo tablespace of the instance. Oracle will handle management of undo data using this undo tablespace. The DATAFILE clause of this clause has the same behavior as described in "DATAFILE Clause".

  Note: If you have specified a value for the UNDO_TABLESPACE initialization parameter in your initialization parameter file before mounting the database, be sure you specify the same name in this clause. If these names differ, Oracle will return an error when you open the database.

• If you omit this clause, Oracle creates a default database with a default undo tablespace named SYS_UNDOTBS and assigns this default tablespace as the undo tablespace of the instance. This undo tablespace allocates disk space from the default files used by the CREATE DATABASE statement, and has an initial extent of 10M. Oracle handles the system-generated datafile as described in "DATAFILE Clause". If Oracle is unable to create the undo tablespace, the entire CREATE DATABASE operation fails.

  See Also: Oracle9i Database Reference for information on opening a database instance in Automatic Undo Management mode using the UNDO_MANAGEMENT parameter Oracle9i Database Administrator's Guide for information on Automatic Undo Management and undo tablespaces CREATE TABLESPACE for information on creating an undo tablespace after database creation

SET STANDBY DATABASE Clause

The SET STANDBY DATABASE clause lets you specify whether your database environment is in no-data-loss mode. In this mode, Oracle places highest priority on maintaining an absolute match between the primary and standby databases. The standby database must be mounted, and no Real Application Clusters instance can have the primary database open, even in exclusive mode.

PROTECTED

Specify PROTECTED to indicate that the standby instance must contain at least one standby archivelog destination to be archived by the logwriter (LGWR) process in order for the primary database to be opened and to remain open in the event the last connection from primary to standby database is lost. In a Real Application Clusters environment, Oracle will verify that the LGWR processes of all instances that have the primary database open archive to the same standby databases.

If a connection to the last standby database is lost, Oracle will shut down the primary instance. Therefore, you should use this setting only if absolute correspondence between the primary and standby databases is more important than availability of the database.

UNPROTECTED

Specify UNPROTECTED to indicate that the instance does not require any standby databases to be maintained by the logwriter process. This is the default.

Use this setting if the absolute correspondence between the primary and standby databases is not as important as availability of the database.

To determine whether a database is in PROTECTED or UNPROTECTED mode, query the STANDBY_DATABASE column of the V$DATABASE dynamic performance view.

See Also: Oracle9i Data Guard Concepts and Administration for information on managing standby databases Oracle9i Database Reference for information on the dynamic performance views

set_time_zone_clause

Use the SET TIME_ZONE clause to set the time zone of the database. You can specify the time zone in two ways:

• By specifying a displacement from UTC (Coordinated Universal Time--formerly Greenwich Mean Time). The valid range of hh:mm is -12:00 to +14:00.

• By specifying a time zone region. To see a listing of valid region names, query the TZNAME column of the V$TIMEZONE_NAMES dynamic performance view.

  See Also: Oracle9i Database Reference for information on the dynamic performance views

Oracle normalizes all TIMESTAMP WITH LOCAL TIME ZONE data to the time zone of the database when the data is stored on disk. If you do not specify the SET TIME_ZONE clause, Oracle uses the operating system's time zone of the server. If the operating system time zone is not a valid Oracle time zone, the database time zone defaults to UTC.

Examples

CREATE DATABASE Example

The following statement creates a database and fully specifies each argument:

CREATE DATABASE sample

CONTROLFILE REUSE 
LOGFILE
   GROUP 1 ('diskx:log1.log', 'disky:log1.log') SIZE 50K, 
   GROUP 2 ('diskx:log2.log', 'disky:log2.log') SIZE 50K 
MAXLOGFILES 5 
MAXLOGHISTORY 100 
MAXDATAFILES 10 
MAXINSTANCES 2 
ARCHIVELOG 
CHARACTER SET UTF8
NATIONAL CHARACTER SET AL16UTF16
DATAFILE  
'disk1:df1.dbf' AUTOEXTEND ON,
'disk2:df2.dbf' AUTOEXTEND ON NEXT 10M MAXSIZE UNLIMITED
DEFAULT TEMPORARY TABLESPACE temp_ts
UNDO TABLESPACE undo_ts 
SET TIME_ZONE = '+02:00';