Maintaining Tempfile in TEMP Tablespace of PDB$SEED in Oracle 12c (12.1.0.2)

During testing recovery procedures for one of the ongoing projects I wanted to test the "complete disaster" recovery scenario. In this scenario I had to recreate also all ASM disks and restore everything from backup.
Actually full backup with RMAN and subsequent restore of a pluggable 12c single-tenant database  was the solution. I will not talk about that as the main point of this post is quite different.

So the recovery was successful but after restoring  the CDB$ROOT and PDB database I found in the alert log the following message:


Errors in file /u01/app/oracle/diag/rdbms/mydb/mydb/trace/mydb_dbw0_28973.trc:
ORA-01157: cannot identify/lock data file 202 - see DBWR trace file
ORA-01110: data file 202: '+DATA/MYDB/FD9AC20F64D244D7E043B6A9E80A2F2F/DATAFILE/pdbseed_temp012015-01-03_12-22-30-pm.dbf'
ORA-17503: ksfdopn:2 Failed to open file +DATA/MYDB/FD9AC20F64D244D7E043B6A9E80A2F2F/DATAFILE/pdbseed_temp012015-01-03_12-22-30-pm.dbf
ORA-15173: entry 'FD9AC20F64D244D7E043B6A9E80A2F2F' does not exist in directory 'MYDB'
Thu Feb 05 09:12:52 2015
Errors in file /u01/app/oracle/diag/rdbms/mydb/mydb/trace/mydb_dbw0_28973.trc:
ORA-01186: file 202 failed verification tests
ORA-01157: cannot identify/lock data file 202 - see DBWR trace file
ORA-01110: data file 202: '+DATA/MYDB/FD9AC20F64D244D7E043B6A9E80A2F2F/DATAFILE/pdbseed_temp012015-01-03_12-22-30-pm.dbf'


The problem was the temp file of the temporary tablespace TEMP in PDB$SEED which is used for creation of pluggable databases. The tempfiles are not part of RMAN backup as they can always be recreated. Although I could live with this error messages as this is single-tennat database with only one pluggable database I wanted to deliver a "clean solution" to the client. Besides I wanted to know how I can solve such problem.

So here is the solution:

$ sqlplus / as sysdba

SQL*Plus: Release 12.1.0.2.0 Production on Thu Feb 5 09:35:11 2015

Copyright (c) 1982, 2014, Oracle.  All rights reserved.


Connected to:
Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
With the Partitioning, Automatic Storage Management, OLAP, Advanced Analytics
and Real Application Testing options

SQL> alter session set container=pdb$seed;

Session altered.

SQL> select open_mode from v$database;

OPEN_MODE
--------------------
READ ONLY


SQL> select name from v$tempfile;

NAME
---------------------------------------------------------------------------------------------------
+DATA/MYDB/FD9AC20F64D244D7E043B6A9E80A2F2F/DATAFILE/pdbseed_temp012015-01-03_12-22-30-pm.dbf


SQL> alter pluggable database pdb$seed close;
alter pluggable database pdb$seed close
*
ERROR at line 1:
ORA-65017: seed pluggable database may not be dropped or altered


SQL> alter session set "_oracle_script"=TRUE;

Session altered.

SQL> alter pluggable database pdb$seed close;

Pluggable database altered.

SQL> alter pluggable database pdb$seed open read write;

Pluggable database altered.

SQL> alter tablespace temp add tempfile '+DATA';

Tablespace altered.
SQL> column name format a100
SQL> select name from v$tempfile;

NAME
-------------------------------------------------------------------------------------------------
+DATA/MYDB/FD9AC20F64D244D7E043B6A9E80A2F2F/DATAFILE/pdbseed_temp012015-01-03_12-22-30-pm.dbf
+DATA/MYDB/0BBEAC43B4250445E0530A0C6D0AEC65/TEMPFILE/temp.299.870860375

SQL>  alter tablespace temp drop tempfile '+DATA/MYDB/FD9AC20F64D244D7E043B6A9E80A2F2F/DATAFILE/pdbseed_temp012015-01-03_12-22-30-pm.dbf';


Tablespace altered.

SQL>  select name from v$tempfile;

NAME
----------------------------------------------------------------------------
+DATA/MYDB/0BBEAC43B4250445E0530A0C6D0AEC65/TEMPFILE/temp.299.870860375



After performed change there were no more error messages during database startup.

The secrete sauce for changing the state of PDB$SEED was setting "alter session set "_oracle_script"=TRUE;". The idea came from this post about changing the open mode of the PDB$SEED database.
Hope this short post will help somebody to resolve his problem with dropping and creating new tempfile in PDB$SEED faster.