About file # In v $ datafile and v $ tempfile #,

About file # In v $ datafile and v $ tempfile #,

The v $ datafile view stores information about data files, and the v $ tempfile view stores information about temporary files. There are file # Fields in both views. Let's take a look at the definition of the official document:

V $ DATAFILE

This view contains datafile information from the control file.

See Also:

"V $ DATAFILE_HEADER", which displays information from datafile headers

Column	Datatype	Description
FILE#	NUMBER	File identification number
CREATION_CHANGE#	NUMBER	Change number at which the datafile was created
CREATION_TIME	DATE	Timestamp of the datafile creation
TS#	NUMBER	Tablespace number
RFILE#	NUMBER	Tablespace relative datafile number
STATUS	VARCHAR2(7)	Type of file (system or user) and its status. Values:OFFLINE,ONLINE,SYSTEM,RECOVER,SYSOFF(An offline file fromSYSTEMTablespace)
ENABLED	VARCHAR2(10)	Describes how accessible the file is from SQL: DISABLED-No SQL access allowed READ ONLY-No SQL updates allowed READ WRITE-Full access allowed UNKNOWN-Shocould not occur unless the control file is already upted
CHECKPOINT_CHANGE#	NUMBER	SCN at last checkpoint
CHECKPOINT_TIME	DATE	Timestamp of the checkpoint #
UNRECOVERABLE_CHANGE#	NUMBER	Last unrecoverable change number made to this datafile. If the database is inARCHIVELOGMode, then this column is updated when an unrecoverable operation completes. If the database is not inARCHIVELOGMode, this column does not get updated.
UNRECOVERABLE_TIME	DATE	Timestamp of the last unrecoverable change. This column is updated only if the database is inARCHIVELOGMode.
LAST_CHANGE#	NUMBER	Last change number made to this datafile (null if the datafile is being changed)
LAST_TIME	DATE	Timestamp of the last change
OFFLINE_CHANGE#	NUMBER	Offline change number of the last offline range. This column is updated only when the datafile is brought online.
ONLINE_CHANGE#	NUMBER	Online change number of the last offline range
ONLINE_TIME	DATE	Online timestamp of the last offline range
BYTES	NUMBER	Current datafile size (in bytes );0If inaccessible
BLOCKS	NUMBER	Current datafile size (in blocks); 0 if inaccessible
CREATE_BYTES	NUMBER	Size when created (in bytes)
BLOCK_SIZE	NUMBER	Block size of the datafile
NAME	VARCHAR2(513)	Name of the datafile
PLUGGED_IN	NUMBER	Describes whether the tablespace is plugged in. The value is1If the tablespace is plugged in and has not been made read/write,0If not.
BLOCK1_OFFSET	NUMBER	Offset from the beginning of the file to where the Oracle generic information begins. The exact length of the file can be computed as follows:BYTES + BLOCK1_OFFSET.
AUX_NAME	VARCHAR2(513)	Auxiliary name that has been set for this fileCONFIGURE AUXNAME
FIRST_NONLOGGED_SCN	NUMBER	First nonlogged SCN
FIRST_NONLOGGED_TIME	DATE	First nonlogged time

V $ TEMPFILE

This view displays tempfile information.

Column	Datatype	Description
FILE#	NUMBER	Absolute file number
CREATION_CHANGE#	NUMBER	Creation System Change Number (SCN)
CREATION_TIME	DATE	Creation time
TS#	NUMBER	Tablespace number
RFILE#	NUMBER	Relative file number in the tablespace
STATUS	VARCHAR2(7)	Status of the file (OFFLINE|ONLINE)
ENABLED	VARCHAR2(10)	Enabled for read and/or write
BYTES	NUMBER	Size of the file in bytes (from the file header)
BLOCKS	NUMBER	Size of the file in blocks (from the file header)
CREATE_BYTES	NUMBER	Creation size of the file (in bytes)
BLOCK_SIZE	NUMBER	Block size for the file
NAME	VARCHAR2(513)	Name of the file

From the preceding document, we can see that in v $ tempfile and v $ datafile, file # indicates that the absolute file is good, while rfile # indicates the relative file number. Here we will verify it:

SQL> l  1* select file#,name from v$tempfileSQL> /     FILE# NAME---------- ------------------------------------------------------------ 1 /home/app/oraten/oradata/oraten/temp01.dbf

SQL> select file#,name from v$datafile;     FILE# NAME---------- ------------------------------------------------------------ 1 /home/app/oraten/oradata/oraten/system01.dbf 2 /home/app/oraten/oradata/oraten/undotbs01.dbf 3 /home/app/oraten/oradata/oraten/sysaux01.dbf 4 /home/app/oraten/oradata/oraten/users01.dbf 5 /home/app/oraten/oradata/oraten/test01.dbf

Both v $ datafile and v $ tempfile have files with absolute file number 1, which is obviously incorrect.

We know that oracle will report an error and display information about the file in the error message when the file cannot be accessed. Next we will simulate the fault of the temporary file.

[Oraten @ yue oraten] $ chmod 000 temp01.dbf [oraten @ yue oraten] $ ll total usage 932180-rw-r ----- 1 oraten dba 7061504 13:59 control01.ctl-rw-r ----- 1 oraten dba 7061504 November 7 13:59 control02.ctl-rw-r ----- 1 oraten dba 7061504 November 7 13:59 control03.ctl-rw-r ----- 1 oraten dba 52429312 November 7 13:44 redo01.log-rw-r ----- 1 oraten dba 52429312 November 7 13:54 redo02.log-rw- r ----- 1 oraten dba 52429312 November 7 13:44 redo03.log-rw-r ----- 1 oraten dba 272637952 November 7 13:49 sysaux01.dbf-rw-r ----- 1 oraten dba 461381632 November 7 13:49 system01.dbf ---------- 1 oraten dba 20979712 November 7 13:39 temp01.dbf-rw-r ----- 1 oraten dba 10493952 November 7 13:44 test01.dbf-rw-r ----- 1 oraten dba 26222592 November 7 13:49 undotbs01.dbf-rw-r ----- 1 oraten dba 5251072 November 7 13:44 users01.dbf

Force start Database

SQL> startup forceORACLE instance started.Total System Global Area  134217728 bytesFixed Size    2094544 bytesVariable Size   88082992 bytesDatabase Buffers   37748736 bytesRedo Buffers    6291456 bytesDatabase mounted.Database opened.SQL> 

Create a temporary table and insert data

SQL> insert into t1 select * from user_tables;insert into t1 select * from user_tables            *ERROR at line 1:ORA-01157: cannot identify/lock data file 101 - see DBWR trace fileORA-01110: data file 101: '/home/app/oraten/oradata/oraten/temp01.dbf'

The temporary file cannot be accessed. The file number shown here is 101. Why?

Modify the db_files parameter to 200 and continue the experiment.

SQL> show parameter db_filesNAME     TYPE VALUE------------------------------------ ----------- ------------------------------db_files     integer 100SQL> alter system set db_files=200 scope=spfile;System altered.SQL> startup forceORACLE instance started.Total System Global Area  134217728 bytesFixed Size    2094544 bytesVariable Size   88082992 bytesDatabase Buffers   37748736 bytesRedo Buffers    6291456 bytesDatabase mounted.Database opened.SQL> insert into t1 select * from user_tables;insert into t1 select * from user_tables            *ERROR at line 1:ORA-01157: cannot identify/lock data file 201 - see DBWR trace fileORA-01110: data file 201: '/home/app/oraten/oradata/oraten/temp01.dbf'

Originally, file # In v $ tempfile is not an absolute file number. The absolute file number of a temporary file is the file # + db_files parameter.

Manual completion !!