Tuesday, February 24, 2015

Table Point in Time Recovery using RMAN

Prior to 12c, in case a table or partition is dropped accidentally, there are certain ways to perform the table/partition recovery which includes Flashback database, database point in time recovery and tablespace point in time recovery.

Starting 12c we can perform point-in-time recovery for a single table
or partition; using RMAN. This new feature enables us to avoid any full database or tablespace point-in-time recovery to recover a dropped table. We need less time, space and resources to perform table recovery using this method.

One point to note is that in case of tablespace point in time recovery, it can be done only if tablepsace is self-contained - and in case of a single table/partition point-in-time recovery, obviously this restriction does not apply.

Flashback drop table may not work if recycle bin has been purged.

I will explain a scenario of a table drop and then its recovery in the following

Create a new user and a table in the schema with some data

SQL> create user c##salman identified by salman;

User created.

SQL> grant dba to c##salman;

Grant succeeded.

Enter user-name: c##salman/salman

Last Successful login time: Thu Jan 15 2015 15:49:25 +08:00

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> create table test as select * from dba_objects;

Table created.

SQL> alter table test move tablespace users;

Table altered.

SQL> insert into test select * from test;

91103 rows created.

SQL> commit;

Commit complete.

SQL> select count(*) from test;

COUNT(*)

----------

182206

SQL>

Take Backup

Assuming database is in archivelog mode. Take a backup of tablespace USERS which has this table in it. Alternatively a full database backup can also be taken.

RMAN> BACKUP FORMAT '/u01/bakcup/back_%u.bak' TABLESPACE USERS;

Drop the Table

Drop the table and note the time. Current SCN can also be noted as we can perform table point in time recovery based on time or SCN. In real time scenario, exact time of table drop may not be known so we would need to be careful in guessing the time.

SQL> drop table test;

Table dropped.

SQL> select sysdate from dual;

SYSDATE

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

16-JAN-15 12:25:02

Perform the recovery using RMAN.

RMAN> RECOVER TABLE 'C##SALMAN'.'TEST' until time "to_date('16-01-15 12:23:00','DD-MM-YY HH24:MI:SS')" auxiliary destination '/u01/backup';

Starting recover at 16-JAN-15

using channel ORA_DISK_1

RMAN-05026: WARNING: presuming following set of tablespaces applies to specified Point-in-Time

List of tablespaces expected to have UNDO segments

Tablespace SYSTEM

Tablespace UNDOTBS1

Creating automatic instance, with SID='iasB'

initialization parameters used for automatic instance:

db_name=CDB

db_unique_name=iasB_pitr_CDB

compatible=12.1.0.2.0

db_block_size=8192

db_files=200

diagnostic_dest=/u02/oracle

_system_trig_enabled=FALSE

sga_target=1584M

processes=200

db_create_file_dest=/u01/backup

log_archive_dest_1='location=/u01/backup'

enable_pluggable_database=true

_clone_one_pdb_recovery=true

#No auxiliary parameter file used

starting up automatic instance CDB

Oracle instance started

Total System Global Area 1660944384 bytes

Fixed Size 2925072 bytes

Variable Size 419433968 bytes

Database Buffers 1224736768 bytes

Redo Buffers 13848576 bytes

Automatic instance created

contents of Memory Script:

{

# set requested point in time

set until time "to_date('16-01-15 12:23:00','DD-MM-YY HH24:MI:SS')";

# restore the controlfile

restore clone controlfile;

# mount the controlfile

sql clone 'alter database mount clone database';

# archive current online log

sql 'alter system archive log current';

}

executing Memory Script

executing command: SET until clause

Starting restore at 16-JAN-15

allocated channel: ORA_AUX_DISK_1

channel ORA_AUX_DISK_1: SID=12 device type=DISK

channel ORA_AUX_DISK_1: starting datafile backup set restore

channel ORA_AUX_DISK_1: restoring control file

channel ORA_AUX_DISK_1: reading from backup piece +DATA/CDB/AUTOBACKUP/2015_01_16/s_869142027.312.869142029

channel ORA_AUX_DISK_1: piece handle=+DATA/CDB/AUTOBACKUP/2015_01_16/s_869142027.312.869142029 tag=TAG20150116T122027

channel ORA_AUX_DISK_1: restored backup piece 1

channel ORA_AUX_DISK_1: restore complete, elapsed time: 00:00:12

output file name=/u01/backup/CDB/controlfile/o1_mf_bckg857l_.ctl

Finished restore at 16-JAN-15

sql statement: alter database mount clone database

sql statement: alter system archive log current

contents of Memory Script:

{

# set requested point in time

set until time "to_date('16-01-15 12:23:00','DD-MM-YY HH24:MI:SS')";

# set destinations for recovery set and auxiliary set datafiles

set newname for clone datafile 1 to new;

set newname for clone datafile 4 to new;

set newname for clone datafile 3 to new;

set newname for clone tempfile 1 to new;

# switch all tempfiles

switch clone tempfile all;

# restore the tablespaces in the recovery set and the auxiliary set

restore clone datafile 1, 4, 3;

switch clone datafile all;

}

executing Memory Script

executing command: SET until clause

executing command: SET NEWNAME

renamed tempfile 1 to /u01/backup/CDB/datafile/o1_mf_temp_%u_.tmp in control file

Starting restore at 16-JAN-15

using channel ORA_AUX_DISK_1

channel ORA_AUX_DISK_1: starting datafile backup set restore

channel ORA_AUX_DISK_1: specifying datafile(s) to restore from backup set

channel ORA_AUX_DISK_1: restoring datafile 00001 to /u01/backup/CDB/datafile/o1_mf_system_%u_.dbf

channel ORA_AUX_DISK_1: restoring datafile 00004 to /u01/backup/CDB/datafile/o1_mf_undotbs1_%u_.dbf

channel ORA_AUX_DISK_1: restoring datafile 00003 to /u01/backup/CDB/datafile/o1_mf_sysaux_%u_.dbf

channel ORA_AUX_DISK_1: reading from backup piece /u01/backup/db_0vpss33u_1_1.bak

channel ORA_AUX_DISK_1: piece handle=/u01/backup/db_0vpss33u_1_1.bak tag=TAG20150116T121350

channel ORA_AUX_DISK_1: restored backup piece 1

channel ORA_AUX_DISK_1: restore complete, elapsed time: 00:04:16

Finished restore at 16-JAN-15

datafile 1 switched to datafile copy

input datafile copy RECID=6 STAMP=869152403 file name=/u01/backup/CDB/datafile/o1_mf_system_bckg8n3n_.dbf

datafile 4 switched to datafile copy

input datafile copy RECID=7 STAMP=869152403 file name=/u01/backup/CDB/datafile/o1_mf_undotbs1_bckg8n49_.dbf

datafile 3 switched to datafile copy

input datafile copy RECID=8 STAMP=869152403 file name=/u01/backup/CDB/datafile/o1_mf_sysaux_bckg8n44_.dbf

contents of Memory Script:

{

# set requested point in time

set until time "to_date('16-01-15 12:23:00','DD-MM-YY HH24:MI:SS')";

# online the datafiles restored or switched

sql clone "alter database datafile 1 online";

sql clone "alter database datafile 4 online";

sql clone "alter database datafile 3 online";

# recover and open database read only

recover clone database tablespace "SYSTEM", "UNDOTBS1", "SYSAUX";

sql clone 'alter database open read only';

}

executing Memory Script

executing command: SET until clause

sql statement: alter database datafile 1 online

sql statement: alter database datafile 4 online

sql statement: alter database datafile 3 online

Starting recover at 16-JAN-15

using channel ORA_AUX_DISK_1

starting media recovery

archived log for thread 1 with sequence 43 is already on disk as file +DATA/CDB/ARCHIVELOG/2015_01_16/thread_1_seq_43.313.869142101

archived log for thread 1 with sequence 44 is already on disk as file +DATA/CDB/ARCHIVELOG/2015_01_16/thread_1_seq_44.306.869142107

archived log for thread 1 with sequence 45 is already on disk as file +DATA/CDB/ARCHIVELOG/2015_01_16/thread_1_seq_45.314.869142107

archived log for thread 1 with sequence 46 is already on disk as file +DATA/CDB/ARCHIVELOG/2015_01_16/thread_1_seq_46.315.869142107

archived log for thread 1 with sequence 47 is already on disk as file +DATA/CDB/ARCHIVELOG/2015_01_16/thread_1_seq_47.316.869151219

archived log file name=+DATA/CDB/ARCHIVELOG/2015_01_16/thread_1_seq_43.313.869142101 thread=1 sequence=43

archived log file name=+DATA/CDB/ARCHIVELOG/2015_01_16/thread_1_seq_44.306.869142107 thread=1 sequence=44

archived log file name=+DATA/CDB/ARCHIVELOG/2015_01_16/thread_1_seq_45.314.869142107 thread=1 sequence=45

archived log file name=+DATA/CDB/ARCHIVELOG/2015_01_16/thread_1_seq_46.315.869142107 thread=1 sequence=46

archived log file name=+DATA/CDB/ARCHIVELOG/2015_01_16/thread_1_seq_47.316.869151219 thread=1 sequence=47

media recovery complete, elapsed time: 00:00:03

Finished recover at 16-JAN-15

sql statement: alter database open read only

contents of Memory Script:

{

sql clone "create spfile from memory";

shutdown clone immediate;

startup clone nomount;

sql clone "alter system set control_files =

''/u01/backup/CDB/controlfile/o1_mf_bckg857l_.ctl'' comment=

''RMAN set'' scope=spfile";

shutdown clone immediate;

startup clone nomount;

# mount database

sql clone 'alter database mount clone database';

}

executing Memory Script

sql statement: create spfile from memory

database closed

database dismounted

Oracle instance shut down

connected to auxiliary database (not started)

Oracle instance started

Total System Global Area 1660944384 bytes

Fixed Size 2925072 bytes

Variable Size 419433968 bytes

Database Buffers 1224736768 bytes

Redo Buffers 13848576 bytes

sql statement: alter system set control_files = ''/u01/backup/CDB/controlfile/o1_mf_bckg857l_.ctl'' comment= ''RMAN set'' scope=spfile

Oracle instance shut down

connected to auxiliary database (not started)

Oracle instance started

Total System Global Area 1660944384 bytes

Fixed Size 2925072 bytes

Variable Size 419433968 bytes

Database Buffers 1224736768 bytes

Redo Buffers 13848576 bytes

sql statement: alter database mount clone database

contents of Memory Script:

{

# set requested point in time

set until time "to_date('16-01-15 12:23:00','DD-MM-YY HH24:MI:SS')";

# set destinations for recovery set and auxiliary set datafiles

set newname for datafile 6 to new;

# restore the tablespaces in the recovery set and the auxiliary set

restore clone datafile 6;

switch clone datafile all;

}

executing Memory Script

executing command: SET until clause

executing command: SET NEWNAME

Starting restore at 16-JAN-15

allocated channel: ORA_AUX_DISK_1

channel ORA_AUX_DISK_1: SID=178 device type=DISK

channel ORA_AUX_DISK_1: starting datafile backup set restore

channel ORA_AUX_DISK_1: specifying datafile(s) to restore from backup set

channel ORA_AUX_DISK_1: restoring datafile 00006 to /u01/backup/IASB_PITR_CDB/datafile/o1_mf_users_%u_.dbf

channel ORA_AUX_DISK_1: reading from backup piece /u01/backup/db_0vpss33u_1_1.bak

channel ORA_AUX_DISK_1: piece handle=/u01/backup/db_0vpss33u_1_1.bak tag=TAG20150116T121350

channel ORA_AUX_DISK_1: restored backup piece 1

channel ORA_AUX_DISK_1: restore complete, elapsed time: 00:00:07

Finished restore at 16-JAN-15

datafile 6 switched to datafile copy

input datafile copy RECID=10 STAMP=869152483 file name=/u01/backup/IASB_PITR_CDB/datafile/o1_mf_users_bckglvqp_.dbf

contents of Memory Script:

{

# set requested point in time

set until time "to_date('16-01-15 12:23:00','DD-MM-YY HH24:MI:SS')";

# online the datafiles restored or switched

sql clone "alter database datafile 6 online";

# recover and open resetlogs

recover clone database tablespace "USERS", "SYSTEM", "UNDOTBS1", "SYSAUX" delete archivelog;

alter clone database open resetlogs;

}

executing Memory Script

executing command: SET until clause

sql statement: alter database datafile 6 online