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Oracle® Database SQL Language Reference
11g Release 2 (11.2)

Part Number E17118-03
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file_specification

Purpose

Use one of the file_specification forms to specify a file as a data file or temp file, or to specify a group of one or more files as a redo log file group. If you are storing your files in Oracle Automatic Storage Management (Oracle ASM) disk groups, then you can further specify the file as a disk group file.

A file_specification can appear in the following statements:

Prerequisites

You must have the privileges necessary to issue the statement in which the file specification appears.

Syntax

file_specification::=

Description of file_specification.gif follows
Description of the illustration file_specification.gif

datafile_tempfile_spec::=

Description of datafile_tempfile_spec.gif follows
Description of the illustration datafile_tempfile_spec.gif

(size_clause::=)

redo_log_file_spec::=

Description of redo_log_file_spec.gif follows
Description of the illustration redo_log_file_spec.gif

(size_clause::=)

ASM_filename ::=

Description of asm_filename.gif follows
Description of the illustration asm_filename.gif

fully_qualified_file_name::=

Description of fully_qualified_file_name.gif follows
Description of the illustration fully_qualified_file_name.gif

numeric_file_name::=

Description of numeric_file_name.gif follows
Description of the illustration numeric_file_name.gif

incomplete_file_name::=

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Description of the illustration incomplete_file_name.gif

alias_file_name::=

Description of alias_file_name.gif follows
Description of the illustration alias_file_name.gif

autoextend_clause::=

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Description of the illustration autoextend_clause.gif

(size_clause::=)

maxsize_clause::=

Description of maxsize_clause.gif follows
Description of the illustration maxsize_clause.gif

(size_clause::=)

Semantics

This section describes the semantics of file_specification. For additional information, refer to the SQL statement in which you specify a data file, temp file, redo log file, or Oracle ASM disk group or disk group file.

datafile_tempfile_spec

Use this clause to specify the attributes of data files and temp files if your database storage is in a file system or on raw devices or in Oracle ASM disk groups.

redo_log_file_spec

Use this clause to specify the attributes of redo log files if your database storage is in a file system or on raw devices or in Oracle ASM disk groups.

filename

Use filename for files stored in a file system or on raw devices. The filename can specify either a new file or an existing file. For a new file:

For an existing file, specify the name of either a data file, temp file, or a redo log file member. The filename can contain only single-byte characters from 7-bit ASCII or EBCDIC character sets. Multibyte characters are not valid.

The filename can include a path prefix. If you do not specify such a path prefix, then the database adds the path prefix for the default storage location, which is platform dependent.

A redo log file group can have one or more members (copies). Each filename must be fully specified according to the conventions for your operating system.

The way the database interprets filename also depends on whether you specify it with the SIZE and REUSE clauses.

ASM_filename

Use a form of ASM_filename for files stored in Oracle ASM disk groups. You can create or refer to data files, temp files, and redo log files with this syntax.

All forms of ASM_filename begin with the plus sign (+) followed by the name of the disk group. You can determine the names of all Oracle ASM disk groups by querying the V$ASM_DISKGROUP view.

See Also:

Oracle Automatic Storage Management Administrator's Guide for information on using Oracle ASM

fully_qualified_file_name

When you create a file in an Oracle ASM disk group, the file receives a system-generated fully qualified Oracle ASM filename. You can use this form only when referring to an existing Oracle ASM file. Therefore, if you are using this form during file creation, you must also specify REUSE.

You can determine the fully qualified names of Oracle ASM files by querying the dynamic performance view appropriate for the file type (for example V$DATAFILE for data files, V$CONTROLFILE for control files, and so on). You can also obtain the filenumber and incarnation_number portions of the fully qualified names by querying the V$ASM_FILE view.

Table 8-1 Oracle File Types and Oracle ASM File Type Tags

Oracle ASM file_type Description Oracle ASM file_type_tag Comments

CONTROLFILE

Control files and backup control files

Current

Backup

DATAFILE

Data files and data file copies

tsname

Tablespace into which the file is added

ONLINELOG

Online logs

group_group#

ARCHIVELOG

Archive logs

thread_thread#_seq_sequence#

TEMPFILE

Temp files

tsname

Tablespace into which the file is added

BACKUPSET

Data file and archive log backup pieces; data file incremental backup pieces

hasspfile_timestamp

hasspfile can take one of two values: s indicates that the backup set includes the spfile; n indicates that the backup set does not include the spfile.

PARAMETERFILE

Persistent parameter files

spfile

DAATAGUARDCONFIG

Data Guard configuration file

db_unique_name

Data Guard uses the value of the DB_UNIQUE_NAME initialization parameter.

FLASHBACK

Flashback logs

log_log#

CHANGETRACKING

Block change tracking data

ctf

Used during incremental backups

DUMPSET

Data Pump dumpset

user_obj#_file#

Dump set files encode the user name, the job number that created the dump set, and the file number as part of the tag.

XTRANSPORT

Data file convert

tsname

AUTOBACKUP

Automatic backup files

hasspfile_timestamp

hasspfile can take one of two values: s indicates that the backup set includes the spfile; n indicates that the backup set does not include the spfile.


numeric_file_name

A numeric Oracle ASM filename is similar to a fully qualified filename except that it uses only the unique filenumber.incarnation_number string. You can use this form only to refer to an existing file. Therefore, if you are using this form during file creation, you must also specify REUSE.

incomplete_file_name

Incomplete Oracle ASM filenames are used during file creation only. If you specify the disk group name alone, then Oracle ASM uses the appropriate default template for the file type. For example, if you are creating a data file in a CREATE TABLESPACE statement, Oracle ASM uses the default DATAFILE template to create an Oracle ASM data file. If you specify the disk group name with a template, then Oracle ASM uses the specified template to create the file. In both cases, Oracle ASM also creates a fully qualified filename.

template_name A template is a named collection of attributes. You can create templates and apply them to files in a disk group. You can determine the names of all Oracle ASM template names by querying the V$ASM_TEMPLATE data dictionary view. Refer to diskgroup_template_clauses for instructions on creating Oracle ASM templates.

You can specify template only during file creation. It appears in the incomplete and alias name forms of the ASM_filename diagram:

alias_file_name

An alias is a user-friendly name for an Oracle ASM file. You can use alias filenames during file creation or reference. You can specify a template with an alias, but only during file creation. To determine the alias names for Oracle ASM files, query the V$ASM_ALIAS data dictionary view.

If you are specifying an alias during file creation, then refer to diskgroup_directory_clauses and diskgroup_alias_clauses for instructions on specifying the full alias name.

SIZE Clause

Specify the size of the file in bytes. Use K, M, G, or T to specify the size in kilobytes, megabytes, gigabytes, or terabytes.

BLOCKSIZE Clause

Specify BLOCKSIZE to override the operating system-dependent sector size. If you omit this clause, then the database uses the operating system-dependent sector size as the block size.

When you add a redo log file to a 512-byte sector disk or to a 4KB sector disk with 512-byte emulation, the blocksize of the new file must be the original platform base block size or 4KB.

All logs within a log group must have the same block size. Two log groups created on separate disks can have different block sizes. However, the mixed configuration introduces overhead at every log switch. Oracle recommends that you create all log files with the same block size.

This clause is useful when the 4K sector size is in use, but you want to optimize disk space use rather than performance. In such a case you can override the operating system sector size by specifying BLOCKSIZE 512 or, for HP-UX, BLOCKSIZE 1024.

REUSE

Specify REUSE to allow Oracle to reuse an existing file.

Restriction on the REUSE Clause You cannot specify REUSE unless you have specified filename.

Whenever Oracle uses an existing file, the previous contents of the file are lost.

autoextend_clause

The autoextend_clause is valid for data files and temp files but not for redo log files. Use this clause to enable or disable the automatic extension of a new or existing data file or temp file. If you omit this clause, then:

ON Specify ON to enable autoextend.

OFF Specify OFF to turn off autoextend if is turned on. 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, then 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. 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 data file.

UNLIMITED Use the UNLIMITED clause if you do not want to limit the disk space that Oracle can allocate to the data file or temp file.

Restriction on the autoextend_clause You cannot specify this clause as part of the datafile_tempfile_spec in a CREATE CONTROLFILE statement or in an ALTER DATABASE CREATE DATAFILE clause.

Examples

Specifying a Log File: Example The following statement creates a database named payable that has two redo log file groups, each with two members, and one data file:

CREATE DATABASE payable 
   LOGFILE GROUP 1 ('diska:log1.log', 'diskb:log1.log') SIZE 50K, 
           GROUP 2 ('diska:log2.log', 'diskb:log2.log') SIZE 50K 
   DATAFILE 'diskc:dbone.dbf' SIZE 30M; 

The first file specification in the LOGFILE clause specifies a redo log file group with the GROUP value 1. This group has members named 'diska:log1.log' and 'diskb:log1.log', each 50 kilobytes in size.

The second file specification in the LOGFILE clause specifies a redo log file group with the GROUP value 2. This group has members named 'diska:log2.log' and 'diskb:log2.log', also 50 kilobytes in size.

The file specification in the DATAFILE clause specifies a data file named 'diskc:dbone.dbf', 30 megabytes in size.

Each file specification specifies a value for the SIZE parameter and omits the REUSE clause, so none of these files can already exist. Oracle must create them.

Adding a Log File: Example The following statement adds another redo log file group with two members to the payable database:

ALTER DATABASE payable 
   ADD LOGFILE GROUP 3 ('diska:log3.log', 'diskb:log3.log') 
   SIZE 50K REUSE; 

The file specification in the ADD LOGFILE clause specifies a new redo log file group with the GROUP value 3. This new group has members named 'diska:log3.log' and 'diskb:log3.log', each 50 kilobytes in size. Because the file specification specifies the REUSE clause, each member can (but need not) already exist.

The following statement adds a logfile group 5 with member log files on migration target disks 4k_disk_a and 4k_disk_b. After executing this statement, you can switch existing log files on disks with 512-byte block size to logs with 4K block size using the switch_logfile_clause.

ALTER DATABASE ADD LOGFILE GROUP 5
     ('4k_disk_a:log5.log', '4k_disk_b:log5.log')
     SIZE 100M BLOCKSIZE 4096 REUSE;

Specifying a Data File: Example The following statement creates a tablespace named stocks that has three data files:

CREATE TABLESPACE stocks 
   DATAFILE 'stock1.dbf' SIZE 10M, 
            'stock2.dbf' SIZE 10M,
            'stock3.dbf' SIZE 10M; 

The file specifications for the data files specify files named 'diskc:stock1.dbf', 'diskc:stock2.dbf', and 'diskc:stock3.dbf'.

Adding a Data File: Example The following statement alters the stocks tablespace and adds a new data file:

ALTER TABLESPACE stocks 
   ADD DATAFILE 'stock4.dbf' SIZE 10M REUSE; 

The file specification specifies a data file named 'stock4.dbf'. If the filename does not exist, then Oracle simply ignores the REUSE keyword.

Using a Fully Qualified Oracle ASM Data File Name: Example When using Oracle ASM, the following syntax shows how to use the fully_qualified_file_name clause to bring online a data file in a hypothetical database, testdb:

ALTER DATABASE testdb 
   DATAFILE '+dgroup_01/testdb/datafile/system.261.1' ONLINE;