Oracle 12.1版本中，UNDO表空间仅存在CDB级别（共享UNDO），来自于AskScuti博客园。
Oracle 12.2版本开始，UNDO表空间同时可以存在每个PDB级别（本地UNDO）。
MOS 文档 ID 2560841.1 使用版本：Oracle Database - Enterprise Edition - Version 12.2.0.1 及之后版本
目录
1. 确认是否开启本地UNDO
2. 关闭当前PDB并以受限模式打开
3. 创建新的UNDO表空间并切换
4. 删除旧的UNDO表空间并重启
1. 确认是否开启本地UNDO
SQL> select property_name, property_value from database_properties where property_name=‘LOCAL_UNDO_ENABLED‘; PROPERTY_NAME PROPERTY_VALUE ----------------------- --------------- LOCAL_UNDO_ENABLED TRUE
2. 关闭当前PDB并以受限模式打开
SQL> show pdbs CON_ID CON_NAME OPEN MODE RESTRICTED ---------- ---------- ---------- ---------- 2 PDB$SEED READ ONLY NO 3 PDB1 READ WRITE NO
SQL> alter pluggable database pdb1 close; Pluggable database altered. SQL> alter pluggable database pdb1 open restricted; Pluggable database altered.
3. 创建新的UNDO表空间并切换
SQL> alter session set container=pdb1; Session altered SQL> show pdbs CON_ID CON_NAME OPEN MODE RESTRICTED ---------- ---------- ---------- ---------- 3 PDB1 READ WRITE YES SQL> show parameter undo NAME TYPE VALUE -------------------- ------------ -------- temp_undo_enabled boolean FALSE undo_management string AUTO undo_retention integer 900 undo_tablespace string UNDOTBS1 SQL> select name from v$datafile; NAME ----------------------------------------------- /u01/app/oracle/oradata/CDB2/PDB1/system01.dbf /u01/app/oracle/oradata/CDB2/PDB1/sysaux01.dbf /u01/app/oracle/oradata/CDB2/PDB1/undotbs01.dbf /u01/app/oracle/oradata/CDB2/PDB1/users01.dbf SQL> create undo tablespace undotbs2 datafile ‘/u01/app/oracle/oradata/CDB2/PDB1/undotbs201.dbf‘ size 50m autoextend on; Tablespace created. SQL> alter system set undo_tablespace=undotbs2; System altered. SQL> show parameter undo_tablespace NAME TYPE VALUE ----------------- ------- -------- undo_tablespace string UNDOTBS2
4. 删除旧的UNDO表空间并重启
SQL> drop tablespace undotbs1 including contents and datafiles; Tablespace dropped. SQL> alter pluggable database pdb1 close; Pluggable database altered. SQL> alter pluggable database pdb1 open; Pluggable database altered. SQL> show pdbs CON_ID CON_NAME OPEN MODE RESTRICTED ---------- ---------- ---------- ---------- 3 PDB1 READ WRITE NO
在PDB级别中如何切换或重建UNDO表空间(文档 ID 2560841.1)
原文：https://www.cnblogs.com/askscuti/p/11266465.html