前言
因磁盘空间不足，需要将undo表空间迁移到其它的存储空间
本文介绍如何优雅的删除undo表空间，并在新的存储空间中创建新的undo表空间
详细操作步骤如下：
1、查看默认undo表空间
SQL>show parameter undo
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
undo_management string AUTO
undo_retention integer 900
undo_tablespace string UNDOTBS
2、查看undo表空间使用情况
SQL>set linesize 1000
SQL>set pagesize 1000
SQL>col usagep for a10
SQL>col tablespace_name for a20
SQL>select ff.s tablespace_name,ff.b total,(ff.b - fr.b) usage,fr.b free,round((ff.b-fr.b) / ff.b * 100) || '%' usagepfrom (select tablespace_name s, sum(bytes) / 1024 / 1024 bfrom dba_data_filesgroup by tablespace_name) ff,(select tablespace_name s, sum(bytes) / 1024 / 1024 bfrom dba_free_spacegroup by tablespace_name) frwhere ff.s = fr.s order by round ((ff.b - fr.b) / ff.b * 100);
TABLESPACE_NAME TOTAL USAGE FREE USAGEP
-------------------- ---------- ---------- ---------- ----------
UNDOTBS 18200 70.9375 18129.0625 0%
3、查看undo表空间数据文件
SQL>select file_id,file_name,tablespace_name,status,autoextensible,bytes/1024/1024 MB from dba_data_files;FILE_ID FILE_NAME TABLESPACE_NAME STATUS AUTOEXTENSIBLE MB
---------- ------------------------------------------------------------ -------------------- --------- --------------- ----------
34 +DATA/orcl/datafile/undotbs.273.1079005483 UNDOTBS AVAILABLE YES 18200
4、创建新的undo表空间
SQL>create undo tablespace undotbs1 datafile '+DATA' size 100m autoextend on;
Tablespace created.
5、设置默认的undo表空间
SQL>alter system set undo_tablespace=UNDOTBS1 scope=both;
System altered.
6、查看修改后的undo表空间
SQL>show parameter undo
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
undo_management string AUTO
undo_retention integer 900
undo_tablespace string UNDOTBS1
7、告警日志提示
Undo Tablespace 48 moved to Pending Switch-Out state.
表示正在迁移undo数据到新的undo表空间
当出现**Undo Tablespace 48 successfully switched out.**表示迁移完成，可以删除旧的undo表空间了。
查看正在使用旧的undo表空间：未选择表示没有正在使用，可以删除旧的undo表空间。
SQL>select * from dba_rollback_segs where tablespace_name='UNDOTBS' and status='ONLINE';
no rows selected
8、删除旧的undo表空间
SQL>drop tablespace undotbs including contents and datafiles;
Tablespace dropped.
9、undo表空间迁移过程监控
9.1、查看正在使用的undo段
SQL>select segment_name,owner,tablespace_name,status
from dba_rollback_segs
where tablespace_name = 'UNDOTBS' and status = 'ONLINE';
9.2、查看哪个用户在使用undo段
SQL>select s.username,s.status,s.sid, u.namefrom v$transaction t, v$rollstat r, v$rollname u, v$session swhere s.taddr = t.addrand t.xidusn = r.usnand r.usn = u.usnorder by s.username;
9.3、查看使用旧的undo表空间的状态是否有online状态
SQL>select * from dba_rollback_segs where tablespace_name='UNDOTBS' and status='ONLINE';
SEGMENT_NAME OWNER TABLESPACE_NAME SEGMENT_ID FILE_ID BLOCK_ID INITIAL_EXTENT NEXT_EXTENT MIN_EXTENTS MAX_EXTENTS PCT_INCREASE STATUS
------------------------------ ------ -------------------- ---------- ---------- ---------- -------------- ----------- ----------- ----------- ------------ ------
_SYSSMU129_1627357485$ PUBLIC UNDOTBS 129 34 272 131072 65536 2 32765 ONLINE
9.4、编写正在占用undo表空间的kill语句
SQL>SELECT 'alter system kill session '''||s.sid|| ','||s.serial#|| ''''||';'FROM v$session s,v$transaction t,v$rollname r,v$rollstat g,dba_rollback_segs h,v$sqlarea iWHERE t.addr = s.taddrAND t.xidusn = r.usnAND r.usn = g.usnand r.name = h.segment_nameAND s.PREV_SQL_ID=i.SQL_ID and h.tablespace_name='UNDOTBS' and s.status='INACTIVE' ;
