如何正確的刪除表空間資料檔案

應該使用如下的命令刪除：

ALTER TABLESPACE TEST DROP DATAFILE 3;

參考mos文章：

Unable to Drop a Datafile From the Tablespace Using Alter Tablespace Command (文件 ID 1050261.1)

違反下列任何一個條件，該datafile均不能被drop：

1）必須為空，否則會報：ORA-03262: the file is non-empty。值得注意的是，non-empty的含義是有extent被分配給了table，而不是該table中有無rows，此時若是使用drop table xxx是不行的，必須使用 drop table xxx purge;或者在已經使用了drop table xxx的情況下，再使用purge table “xxx表在回收站中的名稱”來purge該表，否則空間還是不釋放，datafile依然drop不掉。

2）不能是所屬表空間的第一個file

  以上兩者可以透過drop tablespace來達到目的。

3）不能在read-only表空間中。 ---經測試是可以的

4）不能被offline，否則會報：ORA-03264: cannot drop offline datafile of locally managed tablespace

 針對該報錯，解決方法為：

[oracle@rhel6 u01]$ oerr ora 3264  

03264, 00000, "cannot drop offline datafile of locally managed tablespace"  

// *Cause:  Trying to drop offline datafile in lmts  

// *Action: Try to drop file afetr making it online   

5） Cannot be a datafile that is part of the system tablespace, even if it is not the first datafile of the system tablespace --該條來源於How to Drop a Datafile From a Tablespace (文件 ID 111316.1)

若使用alter database datafile 3 offline drop;並不會刪除資料檔案，這個時候可以先online後再用alter tablespace test drop datafile 3;刪除，若執行alter database  datafile 3 offline drop;後並OS級別刪除了資料檔案，那麼需要使用alter database create datafile 3 as '/u03/app/oracle/oradata/ora1024g/sysaux01.dbf';來新增一個資料檔案，然後再執行recover並online後再用alter tablespace test drop datafile 3;命令刪除。

ALTER DATABASE DATAFILE '/u02/oracle/rbdb1/stuff01.dbf' ONLINE;

ALTER DATABASE DATAFILE '/u02/oracle/rbdb1/stuff01.dbf' OFFLINE;

ALTER DATABASE DATAFILE '/u02/oracle/rbdb1/users03.dbf' OFFLINE FOR DROP;

Unable to Drop a Datafile From the Tablespace Using Alter Tablespace Command (文件 ID 1050261.1)

In this Document

APPLIES TO:

SYMPTOMS

Attempting to drop a datafile from a tablespace using the 10.2 and higher feature:
 

alter tablespace ... drop datafile ... ;

fails. The errors reported may differ depending on the actual situation. 

ORA-3262: the file is non-empty
ORA-3263: cannot drop the first file of tablespace
ORA-3264: cannot drop offline datafile of locally managed tablespace

ORA-60

Some errors are rather straightforward. However some errors are not, like the ORA-60. While the answer to the most common errors are self explanatory, this note focuses on the ORA-60 self-deadlock error received..

CHANGES

Datafile was lost at the Operating System level, causing the datafile to be in an OFFLINE status. Because the datafile contained some temporary segments and extents, these became invalid or stray. This causes an ORA-60 when trying to drop the datafile from the tablespace.

The datafile may be listed as MISSING in the datafile name, the reason for this is explained in:

Note 1050268.1: Explanation of MISSING keyword in datafile name

CAUSE

To drop a data file or temp file, it:

- Must be empty. 
- Cannot be the first file that was created in the tablespace. 
    In such cases, drop the tablespace instead.
- Cannot be in a read-only tablespace.
- Cannot be offline.

SOLUTION

The missing datafile has left this tablespace in an indeterminate status. The tablespace itself can actually still be used. But when an object located in the missing datafile is accessed, the statement will error-out with:

ORA-376: file 7 cannot be read at this time

The tablespace will need to be dropped as well. The 10gR2 feature to drop a single datafile from a tablespace cannot be use in this situation.. 

The following notes can be used to recover the data:
Note 216683.1: How to Recover Data from a Tablespace When One or Several Datafiles are Lost. 
Note 286355.1: How to Recover OFFLINE Dropped Datafile in ARCHIVELOG MODE

REFERENCES

How to Drop a Datafile From a Tablespace (文件 ID 111316.1)

PURPOSE
  This note explains how a datafile can be removed from a database.  

  Since there can be confusion as to how a datafile can be dropped because of 
  the ALTER DATABASE DATAFILE OFFLINE DROP command, this note explains the 
  steps needed to delete a datafile and, in contrast, when the OFFLINE DROP 
  command is used.
 

SCOPE & APPLICATION
  There are two situations where people may want to 'remove' a datafile from a 
  tablespace:

  1.  You have just mistakenly added a file to a tablespace, or perhaps you 
      made the file much larger than intended and now want to remove it.

  2.  You are involved in a recovery scenario and the database will not start 
      because a datafile is missing.

  This article is meant to discuss situation 1 above.  There are other 
  articles that discuss recovery scenarios where a database cannot be brought 
  online due to missing datafiles.  Please see the 'Related Documents' section 
  at the bottom of this article.

Restrictions on Dropping Datafiles:

 - Datafile Must be empty.
 - Cannot be the first file in the tablespace. In such cases, drop the tablespace instead.
 - Cannot be a datafile that is part of the system tablespace, even if it is not the first datafile of the system tablespace.
 - Cannot be in a read-only tablespace.
 - The datafile cannot be offline.




How to 'DROP' a Datafile from a Tablespace:
===========================================

Version 9.2 and earlier

Before we start with detailed explanations of the process involved, please note
that Oracle does not provide an interface for dropping datafiles in the same 
way that you could drop a schema object such as a table, a view, a user, etc.  
Once you make a datafile part of a tablespace, the datafile CANNOT be removed, 
although we can use some workarounds.
 
Before performing certain operations such as taking tablespaces/datafiles 
offline, and trying to drop them, ensure you have a full backup.

If the datafile you wish to remove is the only datafile in that tablespace, 
simply drop the entire tablespace using:

    DROP TABLESPACE  INCLUDING CONTENTS;

You can confirm how many datafiles make up a tablespace by running the 
following query:

    select file_name, tablespace_name 
    from dba_data_files 
    where tablespace_name ='';

The DROP TABLESPACE command removes the tablespace, the datafile, and the 
tablespace's contents from the data dictionary.  Oracle will no longer have 
access to ANY object that was contained in this tablespace.  The physical 
datafile must then be removed using an operating system command (Oracle NEVER 
physically removes any datafiles).  Depending on which platform you try this 
on, you may not be able to physically delete the datafile until Oracle is 
completely shut down. (For example, on Windows NT, you may have to shutdown 
Oracle AND stop the associated service before the operating system will allow 
you to delete the file - in some cases, file locks are still held by Oracle.) 

If you have more than one datafile in the tablespace, and you do NOT need the 
information contained in that tablespace, or if you can easily recreate the 
information in this tablespace, then use the same command as above:

    DROP TABLESPACE  INCLUDING CONTENTS;

Again, this will remove the tablespace, the datafiles, and the tablespace's 
contents from the data dictionary.  Oracle will no longer have access to ANY 
object that was contained in this tablespace.  You can then use CREATE 
TABLESPACE and re-import the appropriate objects back into the tablespace.

If you have more than one datafile in the tablespace and you wish to keep the 
objects that reside in the other datafile(s) which are part of this tablespace,
then you must export all the objects  inside the affected tablespace.  Gather 
information on the current datafiles within the tablespace by running this 
query:

    select file_name, tablespace_name 
    from dba_data_files 
    where tablespace_name ='';

Make sure you specify the tablespace name in capital letters.

In order to allow you to identify which objects are inside the affected 
tablespace for the purposes of running your export, use the following query:

    select owner,segment_name,segment_type 
    from dba_segments 
    where tablespace_name=''

Now, export all the objects that you wish to keep.

Once the export is done, issue the DROP TABLESPACE tablespace INCLUDING 
CONTENTS.  

Note that this PERMANENTLY removes all objects in this tablespace. Delete the 
datafiles belonging to this tablespace using the operating system. (See the 
comment above about possible problems in doing this.) Recreate the tablespace 
with the datafile(s) desired, then import the objects into that tablespace.  
(This may have to be done at the table level, depending on how the tablespace 
was organized.)  

NOTE:
The ALTER DATABASE DATAFILE  OFFLINE DROP command, is not meant 
to allow you to remove a datafile. What the command really means is that you 
are offlining the datafile with the intention of dropping the tablespace.

If you are running in archivelog mode, you can also use:

    ALTER DATABASE DATAFILE  OFFLINE; 

instead of OFFLINE DROP.  Once the datafile is offline, Oracle no longer 
attempts to access it, but it is still considered part of that tablespace. This
datafile is marked only as offline in the controlfile and there is no SCN 
comparison done between the controlfile and the datafile during startup (This 
also allows you to startup a database with a non-critical datafile missing).  
The entry for that datafile is not deleted from the controlfile to give us the
opportunity to recover that datafile.

New functionality was added with the release of version 10.1 and higher

You can now specify drop tablespace inlcluding contents AND DATAFILES
Refer to Oracle? Database Administrator's Guide 10g Release 1 (10.1) Part Number B10739-01
Chapter 8 managing tablespaces for more detailed explination


Starting with version 10.2 and higher 

You can now alter tablespace drop datafile (except first datafile
of a tablespace)

Refer to the following Oracle Documentation for more details regarding this operation:

For Oracle 10g Release 2:
     Oracle? Database Administrator's Guide 10g Release 2 (10.2)Part Number B14231-02 Chapter 9: Dropping Datafiles.

For Oracle 11g:
     Oracle? Database Administrator's Guide 11g Release 1 (11.1) Part Number B28310-04 Chapter 12:  Dropping Datafiles.

If you do not wish to follow any of these procedures, there are other things 
that can be done besides dropping the tablespace.

- If the reason you wanted to drop the file is because you mistakenly created 
  the file of the wrong size, then consider using the RESIZE command.  
  See 'Related Documents' below.

- If you really added the datafile by mistake, and Oracle has not yet allocated
  any space within this datafile, then you can use ALTER DATABASE DATAFILE 
   RESIZE; command to make the file smaller than 5 Oracle blocks. If 
  the datafile is resized to smaller than 5 oracle blocks, then it will never 
  be considered for extent allocation. At some later date, the tablespace can 
  be rebuilt to exclude the incorrect datafile.


RELATED DOCUMENTS
----------------- Note 30910.1 -  Recreating database objects Note 1013221.6 - Recovering from a lost datafile in a ROLLBACK tablespace Note 198640.1 - How to Recover from a Lost Datafile with Different Scenarios Note 1060605.6 - Recover A Lost Datafile With No Backup Note 1029252.6 - How to resize a datafile

The information in this document applies to: 

Symptoms

You have offline dropped a datafile in archivelog mode
You know that once you drop a datafile you need to recreate the tablespace containing that datafile
You can not do that as this is a Big tablespace 
You want that datafile to be again part of the database
even though you do not want that datafile to contain any objects
 
Changes

You can recover the offline datafile and then make it online
further as you do not want any objects to be allocated to that datafile 
you can resize it to a very small size ( remember it can only be done if the datafile is empty .........
you can not resize a datafile below it's high water mark)


Example
==========


SQL> archive log list
Database log mode              Archive Mode
Automatic archival             Enabled
Archive destination            /h01/app/oracle/product/9.2.0/dbs/arch
Oldest online log sequence     207
Next log sequence to archive   209
Current log sequence           209

=======================
shows DB is in archivelog mode
=======================

SQL> alter database datafile 44 offline drop;

Database altered.


SQL> select file#,status from v$datafile where file#=44;

     FILE# STATUS
---------- -------
        44 RECOVER  ======> status in controlfile is recover

SQL> c/datafile/datafile_header
  1* select file#,status from v$datafile_header where file#=44
SQL> /

     FILE# STATUS
---------- -------
        44 OFFLINE  ========>  status in file_header is offline


switch some log file
sql> alter system switch logfile ;
system altered

.
.
.
apply the log ( it will only ask for the log/ corresponding archivelog  which was 
online at that time
It wont ask you to apply any other archivelog

SQL> recover datafile 44;
ORA-00279: change 8252199007514 generated at 10/18/2004 14:21:47 needed for thread 1
ORA-00289: suggestion : /h01/app/oracle/product/9.2.0/dbs/arch1_216.dbf
ORA-00280: change 8252199007514 for thread 1 is in sequence #216


Specify log: {=suggested | filename | AUTO | CANCEL}

Log applied.
Media recovery complete.
SQL> select * from v$log;

    GROUP#    THREAD#  SEQUENCE#      BYTES    MEMBERS ARC STATUS      FIRST_CHANGE# FIRST_TIM
---------- ---------- ---------- ---------- ---------- --- ----------- ------------- ---------
         1          1        248  104857600          1 YES INACTIVE       8.2522E+12 18-OCT-04
         2          1        250  104857600          1 NO  CURRENT        8.2522E+12 18-OCT-04
         3          1        249  104857600          1 YES ACTIVE         8.2522E+12 18-OCT-04



SQL> select file#,status from v$datafile where file#=44;

     FILE# STATUS
---------- -------
        44 OFFLINE

SQL> select file#,status from v$datafile_header where file#=44;

     FILE# STATUS
---------- -------
        44 OFFLINE

SQL> alter database datafile 44 online;

Database altered.

SQL> select file#,status from v$datafile_header where file#=44;

     FILE# STATUS
---------- -------
        44 ONLINE

SQL> select file#,status from v$datafile where file#=44;

     FILE# STATUS
---------- -------
        44 ONLINE


SO the datafile is online

The only case in which the offline dropped datafile can not be online is 
when you have added to many datafiles in the database after offline drop 






Cause

From Documentation
====================

If the database is in NOARCHIVELOG mode, you must specify the DROP clause to take a datafile
 offline. However, the DROP clause does not remove the datafile from the database.
To do that, you must drop the tablespace in which the datafile resides. Until you
 do so, the datafile remains in the data dictionary with the status RECOVER or OFFLINE.
    
 If the database is in ARCHIVELOG mode, Oracle ignores the DROP keyword.