如何正确的删除表空间数据文件

如何正确的删除表空间数据文件

应该使用如下的命令删除：

ALTER TABLESPACE TEST DROP DATAFILE 3;

参考mos文章：

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

违反下列任何一个条件，该datafile均不能被drop：

1）必须为空，否则会报：ORA-03262: the file is non-empty。值得注意的是，non-empty的含义是有extent被分配给了table，而不是该table中有无rows，此时若是使用drop table xxx是不行的，必须使用 drop table xxx purge;或者在已经使用了drop table xxx的情况下，再使用purge table “xxx表在回收站中的名称”来purge该表，否则空间还是不释放，datafile依然drop不掉。

2）不能是所属表空间的第一个file

  以上两者可以通过drop tablespace来达到目的。

3）不能在read-only表空间中。 ---经测试是可以的

4）不能被offline，否则会报：ORA-03264: cannot drop offline datafile of locally managed tablespace

 针对该报错，解决方法为：

[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 --该条来源于How to Drop a Datafile From a Tablespace (文档 ID 111316.1)

若使用alter database datafile 3 offline drop;并不会删除数据文件，这个时候可以先online后再用alter tablespace test drop datafile 3;删除，若执行alter database  datafile 3 offline drop;后并OS级别删除了数据文件，那么需要使用alter database create datafile 3 as '/u03/app/oracle/oradata/ora1024g/sysaux01.dbf';来添加一个数据文件，然后再执行recover并online后再用alter tablespace test drop datafile 3;命令删除。

1.2 对于非归档模式：
如果是非归档模式，只能是offline drop. 因为非归档模式没有归档文件来进行recover操作，当然，如果offline 之后，速度足够块，online redo里的数据还没有被覆盖掉，那么这种情况下，还是可以进行recover的。
 
oracle 11g:
SQL>ALTER DATABASE DATAFILE '/u02/oracle/rbdb1/users03.dbf' OFFLINE FOR DROP;
  
2. alter tablesapce ‘tablespace_name’ drop datafile 'datafile_name'
该语句会删除磁盘上的文件并更新控制文件和数据字典中的信息，删除之后的原数据文件序列号可以重用。
注意，该语句只能是datafile online的时候才可以使用。如果说对应的数据文件已经是offline for drop，那么仅针对 dictionary managed tablespaces 可用。

OFFLINE Specify OFFLINE to take the data file offline. If the database is open,
then you must perform media recovery on the data file before bringing it back
online, because a checkpoint is not performed on the data file before it is
taken offline.

FOR DROP If
the database is in NOARCHIVELOG mode, then you must specify FOR DROP clause to take a data file offline. However,
this clause does not remove the data file from the database. To do that, you
must use an operating system command or drop the tablespace in which the data
file resides. Until you do so, the data file remains in the data dictionary with
the status RECOVER or OFFLINE.

If the database is in ARCHIVELOG mode, then Oracle Database
ignores the FOR DROP clause.

Bringing Data Files Online or Taking Offline in ARCHIVELOG
Mode

To bring an individual data file online,
issue the ALTER DATABASE statement and include the DATAFILE clause. The following statement brings the specified data
file online:

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

To take the same file offline, issue the following statement:

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

Note:

To use this form of the ALTER DATABASE statement, the database must be in ARCHIVELOG mode. This
requirement prevents you from accidentally losing the data file, since taking
the data file offline while in NOARCHIVELOG mode is likely to
result in losing the file.

Taking Data Files Offline in NOARCHIVELOG Mode

To take a data file offline when the database
is in NOARCHIVELOG mode, use the ALTER DATABASE statement with both the DATAFILE and OFFLINE FOR DROP clauses.

• The OFFLINE keyword causes the database to mark the data file OFFLINE, whether or not it is corrupted, so that you can open the
  database.
• The FOR DROP keywords mark the data file for
  subsequent dropping. Such a data file can no longer be brought back online.

  Note:

  This operation does not actually drop the data file. It
  remains in the data dictionary, and you must drop it yourself using one of the
  following methods:

  • An ALTER TABLESPACE ... DROP DATAFILE statement.

    After an OFFLINE FOR DROP, this method works for dictionary managed
    tablespaces only.

  • A DROP TABLESPACE ... INCLUDING CONTENTS AND DATAFILES statement
  • If the preceding methods fail, an operating system command to delete the data
    file. This is the least desirable method, as it leaves references to the data
    file in the data dictionary and control files.

The following statement takes the specified data file offline and marks it to
be dropped:

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

点击(此处)折叠或打开

1. SYS@ora10g> create tablespace ts_dd_lhr datafile '/tmp/ts_dd_lhr01.dbf' size 10M;
2. Tablespace created.
3. SYS@ora10g> alter tablespace ts_dd_lhr drop datafile '/tmp/ts_dd_lhr01.dbf';
4. alter tablespace ts_dd_lhr drop datafile '/tmp/ts_dd_lhr01.dbf'
5. *
6. ERROR at line 1:
7. ORA-03261: the tablespace TS_DD_LHR has only one file
8. SYS@ora10g> alter tablespace ts_dd_lhr add datafile '/tmp/ts_dd_lhr02.dbf' size 10M;
9. Tablespace altered.
10. SYS@ora10g> alter tablespace ts_dd_lhr drop datafile '/tmp/ts_dd_lhr01.dbf';
11. alter tablespace ts_dd_lhr drop datafile '/tmp/ts_dd_lhr01.dbf'
12. *
13. ERROR at line 1:
14. ORA-03263: cannot drop the first file of tablespace TS_DD_LHR
15. SYS@ora10g> alter tablespace ts_dd_lhr drop datafile '/tmp/ts_dd_lhr02.dbf';
16. Tablespace altered.
17. SYS@ora10g> ! ls -l /tmp/ts_dd_lhr0*
18. -rw-r----- 1 oracle oinstall 10493952 Jun 29 14:58 /tmp/ts_dd_lhr01.dbf
19. --------------------------------------------------
20. SYS@ora10g> alter tablespace ts_dd_lhr add datafile '/tmp/ts_dd_lhr02.dbf' size 10M;
21. Tablespace altered.
22. SYS@ora10g> alter database datafile '/tmp/ts_dd_lhr02.dbf' offline drop;
23. Database altered.
24. SYS@ora10g> ! ls -l /tmp/ts_dd_lhr02.dbf
25. -rw-r----- 1 oracle oinstall 10493952 Jun 29 15:17 /tmp/ts_dd_lhr02.dbf
26. SYS@ora10g> alter tablespace ts_dd_lhr drop datafile '/tmp/ts_dd_lhr02.dbf';
27. alter tablespace ts_dd_lhr drop datafile '/tmp/ts_dd_lhr02.dbf'
28. *
29. ERROR at line 1:
30. ORA-03264: cannot drop offline datafile of locally managed tablespace
31. SYS@ora10g> alter database datafile '/tmp/ts_dd_lhr02.dbf' online;
32. alter database datafile '/tmp/ts_dd_lhr02.dbf' online
33. *
34. ERROR at line 1:
35. ORA-01113: file 9 needs media recovery
36. ORA-01110: data file 9: '/tmp/ts_dd_lhr02.dbf'
37. SYS@ora10g> recover datafile 9;
38. Media recovery complete.
39. SYS@ora10g> alter database datafile '/tmp/ts_dd_lhr02.dbf' online;
40. Database altered.
41. SYS@ora10g> alter tablespace ts_dd_lhr drop datafile '/tmp/ts_dd_lhr02.dbf';
42. Tablespace altered.
43. SYS@ora10g> ! ls -l /tmp/ts_dd_lhr02.dbf
44. ls: cannot access /tmp/ts_dd_lhr02.dbf: No such file or directory
45. SYS@orclasm > create table t_ts_dd_lhr tablespace ts_dd_lhr as select * from dual;
46. Table created.
47. SYS@orclasm > truncate table t_ts_dd_lhr;
48. Table truncated.
49. SYS@orclasm >
50. SYS@orclasm > alter tablespace ts_dd_lhr drop datafile '/tmp/ts_dd_lhr02.dbf';
51. alter tablespace ts_dd_lhr drop datafile '/tmp/ts_dd_lhr02.dbf'
52. *
53. ERROR at line 1:
54. ORA-03262: the file is non-empty
55. SYS@orclasm > drop table t_ts_dd_lhr;
56. Table dropped.
57. SYS@orclasm > alter tablespace ts_dd_lhr drop datafile '/tmp/ts_dd_lhr02.dbf';
58. alter tablespace ts_dd_lhr drop datafile '/tmp/ts_dd_lhr02.dbf'
59. *
60. ERROR at line 1:
61. ORA-03262: the file is non-empty
62. SYS@orclasm > purge recyclebin;
63. Recyclebin purged.
64. SYS@orclasm > alter tablespace ts_dd_lhr drop datafile '/tmp/ts_dd_lhr02.dbf';
65. Tablespace altered.
66. SYS@ora10g> create tablespace ts_dd_lhr datafile '/tmp/ts_dd_lhr01.dbf' size 10M;
67. alter tablespace ts_dd_lhr add datafile '/tmp/ts_dd_lhr02.dbf' size 10M;
68. Tablespace created.
69. SYS@ora10g> SYS@ora10g> SYS@ora10g>
70. Tablespace altered.
71. SYS@ora10g>
72. SYS@ora10g> alter tablespace ts_dd_lhr read only;
73. Tablespace altered.
74. SYS@ora10g> select * from dba_tablespaces;
75. TABLESPACE_NAME BLOCK_SIZE INITIAL_EXTENT NEXT_EXTENT MIN_EXTENTS MAX_EXTENTS PCT_INCREASE MIN_EXTLEN STATUS CONTENTS LOGGING FOR EXTENT_MAN ALLOCATIO PLU SEGMEN DEF_TAB_ RETENTION BIG
76. ------------------------------ ---------- -------------- ----------- ----------- ----------- ------------ ---------- --------- --------- --------- --- ---------- --------- --- ------ -------- ----------- ---
77. SYSTEM 8192 65536 1 2147483645 65536 ONLINE PERMANENT LOGGING NO LOCAL SYSTEM NO MANUAL DISABLED NOT APPLY NO
78. UNDOTBS1 8192 65536 1 2147483645 65536 ONLINE UNDO LOGGING NO LOCAL SYSTEM NO MANUAL DISABLED NOGUARANTEE NO
79. SYSAUX 8192 65536 1 2147483645 65536 ONLINE PERMANENT LOGGING NO LOCAL SYSTEM NO AUTO DISABLED NOT APPLY NO
80. TEMP 8192 1048576 1048576 1 0 1048576 ONLINE TEMPORARY NOLOGGING NO LOCAL UNIFORM NO MANUAL DISABLED NOT APPLY NO
81. USERS 8192 65536 1 2147483645 65536 ONLINE PERMANENT LOGGING NO LOCAL SYSTEM NO AUTO DISABLED NOT APPLY NO
82. EXAMPLE 8192 65536 1 2147483645 65536 ONLINE PERMANENT NOLOGGING NO LOCAL SYSTEM YES AUTO DISABLED NOT APPLY NO
83. TS10GTEST 8192 65536 1 2147483645 65536 ONLINE PERMANENT LOGGING NO LOCAL SYSTEM NO AUTO DISABLED NOT APPLY NO
84. HHRIS 8192 65536 1 2147483645 65536 ONLINE PERMANENT LOGGING NO LOCAL SYSTEM NO AUTO DISABLED NOT APPLY NO
85. TS_DD_LHR 8192 65536 1 2147483645 65536 READ ONLY PERMANENT LOGGING NO LOCAL SYSTEM NO AUTO DISABLED NOT APPLY NO
86. 9 rows selected.
87. SYS@ora10g>
88. SYS@ora10g> alter tablespace ts_dd_lhr drop datafile '/tmp/ts_dd_lhr01.dbf';
89. alter tablespace ts_dd_lhr drop datafile '/tmp/ts_dd_lhr01.dbf'
90. *
91. ERROR at line 1:
92. ORA-03263: cannot drop the first file of tablespace TS_DD_LHR
93. SYS@ora10g>
94. SYS@ora10g> alter tablespace ts_dd_lhr drop datafile '/tmp/ts_dd_lhr02.dbf';
95. Tablespace altered.

alter table temp move tablespace test2; 重建索引。
 

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

In this Document

APPLIES TO:

Oracle Database - Enterprise Edition - Version 10.2.0.1 to 11.2.0.1.0 [Release 10.2 to 11.2]
Information in this document applies to any platform.
***Checked for relevance on 01-Nov-2011***
***Checked for relevance on 27-Aug-2014***

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

NOTE:1050268.1 - Explanation of MISSING keyword in datafile name

NOTE:286355.1 - HOW TO RECOVER OFFLINE DROPPED DATAFILE IN ARCHIVELOG MODE

How to Drop a Datafile From a Tablespace (文档 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.