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Oracle 12.2 New Features : Local UNDO and Flashback PDB Database


You can now flashback PDB database exclusively with Local UNDO enabled. In earlier versions, Oracle shares the undo tablespace for CDB and PDB's and creates a common view for transaction and instance recovery done at all CDB and PDB level. With local undo , Oracle has to change this a bit, it has to either maintain records of master cdb and pdb in shared undo and also in Local UNDO for pdb level. I will have to further dig into, but for now this feature is available and flashback is possible.

To do this, Enable Local UNDO on PDB level and restart the database. It will create a undo tablespace automatically and PDB start using it.


SQL> shutdown immediate

SQL> startup upgrade

SQL> alter database local undo on;

SQL> shutdown immediate

SQL> alter pluggable database all open;

SQL> select name,con_id from v$tablespace where name like '%UNDO%' ;

NAME         CON_ID

---------- -------------

UNDOTBS1        1  -- >Root

UNDO_1          2  -- >PDBSEED

UNDO_1          3  -- >PDB1


Do a flashback,

SQL> flashback pluggable database pdb1 to timestamp systimestamp - interval '1' hour;

SQL> alter pluggable database pdb1 open resetlogs;



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