Oracle数据文件收缩

随着数据库的使用，数据文件越来越大，有没有办法将标记为free的block挤掉

相关表：

DBA_DATA_FILES

DBA_DATA_FILES describes database files.

Column	Datatype	NULL	Description
FILE_NAME	VARCHAR2(513)		Name of the database file
FILE_ID	NUMBER	NOT NULL	File identifier number of the database file
TABLESPACE_NAME	VARCHAR2(30)	NOT NULL	Name of the tablespace to which the file belongs
BYTES	NUMBER		Size of the file in bytes
BLOCKS	NUMBER	NOT NULL	Size of the file in Oracle blocks
STATUS	VARCHAR2(9)		File status: AVAILABLE or INVALID (INVALID means that the file number is not in use, for example, a file in a tablespace that was dropped)
RELATIVE_FNO	NUMBER		Relative file number
AUTOEXTENSIBLE	VARCHAR2(3)		Autoextensible indicator
MAXBYTES	NUMBER		Maximum file size in bytes
MAXBLOCKS	NUMBER		Maximum file size in blocks
INCREMENT_BY	NUMBER		Number of Oracle blocks used as autoextension increment
USER_BYTES	NUMBER		The size of the file available for user data. The actual size of the file minus the USER_BYTES value is used to store file related metadata.
USER_BLOCKS	NUMBER		Number of blocks which can be used by the data
ONLINE_STATUS	VARCHAR2(7)		Online status of the file: SYSOFF SYSTEM OFFLINE ONLINE RECOVER

DBA_FREE_SPACE

DBA_FREE_SPACE describes the free extents in all tablespaces in the database.

Note that if a datafile (or entire tablespace) is offline in a locally managed tablespace, you will not see any extent information. If an object has extents in an online file of the tablespace, you will see extent information about the offline datafile. However, if the object is entirely in the offline file, a query of this view will not return any records.

Related View

USER_FREE_SPACE describes the free extents in the tablespaces accessible to the current user.

Column	Datatype	NULL	Description
TABLESPACE_NAME	VARCHAR2(30)		Name of the tablespace containing the extent
FILE_ID	NUMBER		File identifier number of the file containing the extent
BLOCK_ID	NUMBER		Starting block number of the extent
BYTES	NUMBER		Size of the extent (in bytes) --free bytes
BLOCKS	NUMBER		Size of the extent (in Oracle blocks)  --free block
RELATIVE_FNO	NUMBER		Relative file number of the file containing the extent

DBA_EXTENTS

DBA_EXTENTS describes the extents comprising the segments in all tablespaces in the database.

Note that if a datafile (or entire tablespace) is offline in a locally managed tablespace, you will not see any extent information. If an object has extents in an online file of the tablespace, you will see extent information about the offline datafile. However, if the object is entirely in the offline file, a query of this view will not return any records.

Related View

USER_EXTENTS describes the extents comprising the segments owned by the current user's objects. This view does not display the OWNER, FILE_ID, BLOCK_ID, orRELATIVE_FNO columns.

Column	Datatype	NULL	Description
OWNER	VARCHAR2(30)		Owner of the segment associated with the extent
SEGMENT_NAME	VARCHAR2(81)		Name of the segment associated with the extent
PARTITION_NAME	VARCHAR2(30)		Object Partition Name (Set to NULL for non-partitioned objects)
SEGMENT_TYPE	VARCHAR2(18)		Type of the segment: INDEX PARTITION, TABLE PARTITION
TABLESPACE_NAME	VARCHAR2(30)		Name of the tablespace containing the extent
EXTENT_ID	NUMBER		Extent number in the segment
FILE_ID	NUMBER		File identifier number of the file containing the extent
BLOCK_ID	NUMBER		Starting block number of the extent
BYTES	NUMBER		Size of the extent in bytes
BLOCKS	NUMBER		Size of the extent in Oracle blocks
RELATIVE_FNO	NUMBER		Relative file number of the first extent block

SELECT 'alter database datafile '
  ||chr(39)
  ||file_name
  ||chr(39)
  || ' resize '
  || ceil(hwmsize*1.2)
  ||'M;'
FROM
  (SELECT 　　a.file_id,
    a.file_name,
    a.filesize,
    b.freesize,
    　　(a.filesize-b.freesize) usedsize,
    　　c.hwmsize,
    　　c.hwmsize                                  - (a.filesize-b.freesize) unsedsize_belowhwm,
    　　a.filesize                                 - c.hwmsize canshrinksize
  FROM 　　( 　　select file_id,file_name,ROUND(bytes/1024/1024) filesize
  FROM dba_data_files 　　) a,
    　　( 　　select file_id,ROUND(SUM(dfs.bytes)/1024/1024) freesize
  FROM dba_free_space dfs 　　group BY file_id 　　) b,
    　　( 　　select file_id,ROUND(MAX(block_id)*8/1024) HWMsize
  FROM dba_extents 　　group BY file_id) c 　　where a.file_id = b.file_id 　　and a.file_id = c.file_id 　　order BY unsedsize_belowhwm DESC
  )

alter database datafile 'F:\ORACLE\ORADATA\PURPLE\USERS_NEW' resize 5755M;
alter database datafile 'F:\ORACLE\ORADATA\PURPLE\SYSTEM01.DBF' resize 4574M;
alter database datafile 'F:\ORACLE\ORADATA\PURPLE\INDEX_NEW' resize 825M;
alter database datafile 'F:\ORACLE\ORADATA\PURPLE\USERS01.DBF' resize 17980M;
alter database datafile 'F:\ORACLE\ORADATA\PURPLE\SYSAUX01.DBF' resize 670M;
alter database datafile 'F:\ORACLE\ORADATA\PURPLE\EXAMPLE01.DBF' resize 90M;
alter database datafile 'F:\ORACLE\ORADATA\PURPLE\UNDOTBS01.DBF' resize 72M;

总共释放出7G的空间出来。