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Recovering Tables and Table Partitions

摘要

12c 的 rman 有了很大的增強，其中一個亮點就是可以進行表(或分割槽)級別的恢復，相比 TSPITR，recover table 更加快捷、靈活。

介紹概述

在 Oracle 12c 之前，如果誤刪一張表，常規的方法是 Flashback 閃回或 TSPITR。而開啟 flashback 會消耗磁碟空間，且如果被 purge 或者經過 DDL，將無法 flashback。如果需要恢復的表空間過大，TSPITR 會耗時非常久。12c 中提供了Table Recovery 的新特性，可以針對單表（或單個表分割槽）基於時間點進行恢復，該特性用以直接從 RMAN 備份中恢復表的方法，該特性有以下特點：

不影響資料庫中的其他資料庫物件
減少時間和磁碟空間的消耗，和早期的 TSPIRT 工作流程類似
從另一個磁碟路徑恢復表空間
匯出想要的表資料
匯入到原資料庫（可選）

recover table 可以將一個或多個表或表分割槽恢復到指定的時間點，而不會影響其餘的資料庫物件。可以使用以前建立的 RMAN 備份將表和表分割槽恢復到指定的時間點。

該表被恢復到一個輔助例項中，並且可以選擇：

使用 REMAP 選項將恢復的表匯入新表或分割槽
僅在恢復的表中建立 expdp dump 檔案，以便在其他時間進行匯入

先決條件

目標資料庫必須處於讀寫模式。

目標資料庫必須處於 ARCHIVELOG 模式。

您必須擁有表或表分割槽的 RMAN 備份，因為它們存在於要恢復這些物件的時間點。

要恢復單個表分割槽，目標資料庫的 COMPATIBLE 初始化引數必須設定為 11.1.0 或更高。

請確保 AUXILIARY DESTINATION 有足夠的空間來恢復 system、sysaux、undo 以及恢復表所需的表空間。

請注意，表恢復後，輔助目標中的這些檔案將自動刪除

必須使用 AUXILIARY DESTINATION 子句和後面其中一個子句來指定恢復的時間點：UNTIL TIME、UNTIL SCN 或 UNTIL SEQUENCE。

使用限制

屬於SYS模式的表和表分割槽無法恢復。
SYSTEM和SYSAUX表空間中的表和表分割槽無法恢復。
standby資料庫上的表和表分割槽無法恢復。
命名為NOT NULL約束的表不能用REMAP選項恢復。

RMAN從備份中自動處理恢復表或者表分割槽時會執行如下步驟：

 

判斷哪些備份包含需要恢復的表或表分割槽，然後根據指定的時間來進行恢復。

 

判斷目標主機上是否有足夠的空間來建立auxiliary instance，該例項用於處理表或分割槽的恢復。 如果需要的空間不足，那麼RMAN 會報錯並退出恢復操作。

 

建立auxiliary database，並根據指定的時間來恢復指定的表或表分割槽到auxiliary database中。 輔助資料庫的資料檔案位置可以在命令中指定。

 

建立包含恢復表或表分割槽的資料泵檔案（expdp dump file）。 資料泵的名稱和位置也可以在命令中指定。

 

（可選操作）將上一步生產的資料泵檔案匯入到目標例項中。當然也可以選擇不匯入，如果選擇不匯入就必須使用impdp 手工匯入。

 

（可選操作）在目標資料庫中rename 恢復表或表分割槽。

使用場景

RMAN 的表級和表分割槽級恢復在以下場景中非常適用：

（1）需要將非常少量的表恢復至特定的時間點。在這種情況下，TSPITR 不是最有效的解決方案，因為它會將表空間中的所有物件恢復到指定的時間點。

（2）需要恢復已被邏輯損壞或已被 drop 和 purge 的表。

（3） flashback 不可用，比如需要的 undo 資料被覆蓋。

（4） DDL 操作修改表結構後丟失的資料。flashback table 不能跨越 DDL（例如 truncate ）來回滾表。

在這Recover table 過程演示

建立測試表

SQL> create table t_recover_test as select * from dba_objects;

Table created.

SQL> select count(*) from t_recover_test;

COUNT(*)

----------

72652

備份

[oracle@localhost ~]$ rman target /

Recovery Manager: Release 12.2.0.1.0 - Production on Thu Jun 28 21:06:17 2018

connected to target database: PCC (DBID=3164878903)

RMAN> backup database format '/home/oracle/bak/db_%U';

Starting backup at 28-JUN-18

using target database control file instead of recovery catalog

allocated channel: ORA_DISK_1

channel ORA_DISK_1: SID=61 device type=DISK

channel ORA_DISK_1: starting full datafile backup set

channel ORA_DISK_1: specifying datafile(s) in backup set

input datafile file number=00001 name=/home/oracle/oradata/pcc/system01.dbf

input datafile file number=00003 name=/home/oracle/oradata/pcc/sysaux01.dbf

input datafile file number=00004 name=/home/oracle/oradata/pcc/undotbs01.dbf

input datafile file number=00005 name=/home/oracle/oradata/pcc/tbs_zyq01.dbf

input datafile file number=00007 name=/home/oracle/oradata/pcc/users01.dbf

channel ORA_DISK_1: starting piece 1 at 28-JUN-18

channel ORA_DISK_1: finished piece 1 at 28-JUN-18

piece handle=/home/oracle/bak/db_01t6k254_1_1 tag=TAG20180628T215236 comment=NONE

channel ORA_DISK_1: backup set complete, elapsed time: 00:00:15

Finished backup at 28-JUN-18

Starting Control File and SPFILE Autobackup at 28-JUN-18

piece handle=/u01/app/oracle/product/12.2.0.1/dbs/c-3164878903-20180628-00 comment=NONE

Finished Control File and SPFILE Autobackup at 28-JUN-18

恢復表

[oracle@localhost ~]$ rman target /

Recovery Manager: Release 12.2.0.1.0 - Production on Fri Jun 29 00:52:29 2018

connected to target database: PCC (DBID=3164878903)

RMAN> RECOVER TABLE zyq.t_recover_test

until time "to_date('2018-06-28 23:56:06','yyyy-mm-dd hh24:mi:ss')"

AUXILIARY DESTINATION '/data01'

REMAP TABLE zyq.t_recover_test:t_recover_test_map;

Starting recover at 29-JUN-18

using target database control file instead of recovery catalog

allocated channel: ORA_DISK_1

channel ORA_DISK_1: SID=66 device type=DISK

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=' hCed '

initialization parameters used for automatic instance:

db_name=PCC

db_unique_name=hCed_pitr_PCC

compatible=12.2.0

db_block_size=8192

db_files=200

diagnostic_dest=/u01/app/oracle

_system_trig_enabled=FALSE

sga_target=732M

processes=200

db_create_file_dest=/data01

log_archive_dest_1='location=/data01'

#No auxiliary parameter file used

starting up automatic instance PCC

Oracle instance started

Total System Global Area 767557632 bytes

Fixed Size 8625416 bytes

Variable Size 213910264 bytes

Database Buffers 541065216 bytes

Redo Buffers 3956736 bytes

Automatic instance created

contents of Memory Script:

{

# set requested point in time

set until time "to_date('2018-06-28 23:56:06','yyyy-mm-dd 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 29-JUN-18

allocated channel: ORA_AUX_DISK_1

channel ORA_AUX_DISK_1: SID=35 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 /u01/app/oracle/product/12.2.0.1/dbs/c-3164878903-20180628-01

channel ORA_AUX_DISK_1: piece handle=/u01/app/oracle/product/12.2.0.1/dbs/c-3164878903-20180628-01 tag=TAG20180628T234914

channel ORA_AUX_DISK_1: restored backup piece 1

channel ORA_AUX_DISK_1: restore complete, elapsed time: 00:00:02

output file name=/data01/PCC/controlfile/o1_mf_fmcsc00p_.ctl

Finished restore at 29-JUN-18

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('2018-06-28 23:56:06','yyyy-mm-dd 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 /data01/PCC/datafile/o1_mf_temp_%u_.tmp in control file

Starting restore at 29-JUN-18

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 /data01/PCC/datafile/o1_mf_system_%u_.dbf

channel ORA_AUX_DISK_1: restoring datafile 00004 to /data01/PCC/datafile/o1_mf_undotbs1_%u_.dbf

channel ORA_AUX_DISK_1: restoring datafile 00003 to /data01/PCC/datafile/o1_mf_sysaux_%u_.dbf

channel ORA_AUX_DISK_1: reading from backup piece /home/oracle/bak/db_01t6k254_1_1

channel ORA_AUX_DISK_1: piece handle=/home/oracle/bak/db_01t6k254_1_1 tag=TAG20180628T215236

channel ORA_AUX_DISK_1: restored backup piece 1

channel ORA_AUX_DISK_1: restore complete, elapsed time: 00:00:15

Finished restore at 29-JUN-18

datafile 1 switched to datafile copy

input datafile copy RECID=4 STAMP=980038406 file name=/data01/PCC/datafile/o1_mf_system_fmcsc755_.dbf

datafile 4 switched to datafile copy

input datafile copy RECID=5 STAMP=980038406 file name=/data01/PCC/datafile/o1_mf_undotbs1_fmcsc75h_.dbf

datafile 3 switched to datafile copy

input datafile copy RECID=6 STAMP=980038406 file name=/data01/PCC/datafile/o1_mf_sysaux_fmcsc75c_.dbf

contents of Memory Script:

{

# set requested point in time

set until time "to_date('2018-06-28 23:56:06','yyyy-mm-dd 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 29-JUN-18

using channel ORA_AUX_DISK_1

starting media recovery

archived log for thread 1 with sequence 3 is already on disk as file /u01/app/oracle/product/12.2.0.1/dbs/arch1_3_979872889.dbf

archived log for thread 1 with sequence 4 is already on disk as file /u01/app/oracle/product/12.2.0.1/dbs/arch1_4_979872889.dbf

archived log file name=/u01/app/oracle/product/12.2.0.1/dbs/arch1_3_979872889.dbf thread=1 sequence=3

archived log file name=/u01/app/oracle/product/12.2.0.1/dbs/arch1_4_979872889.dbf thread=1 sequence=4

media recovery complete, elapsed time: 00:00:11

Finished recover at 29-JUN-18

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 =

''/data01/PCC/controlfile/o1_mf_fmcsc00p_.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 767557632 bytes

Fixed Size 8625416 bytes

Variable Size 213910264 bytes

Database Buffers 541065216 bytes

Redo Buffers 3956736 bytes

sql statement: alter system set control_files = ''/data01/PCC/controlfile/o1_mf_fmcsc00p_.ctl'' comment= ''RMAN set'' scope=spfile

Oracle instance shut down

connected to auxiliary database (not started)

Oracle instance started

Total System Global Area 767557632 bytes

Fixed Size 8625416 bytes

Variable Size 213910264 bytes

Database Buffers 541065216 bytes

Redo Buffers 3956736 bytes

sql statement: alter database mount clone database

contents of Memory Script:

{

# set requested point in time

set until time "to_date('2018-06-28 23:56:06','yyyy-mm-dd hh24:mi:ss')";

# set destinations for recovery set and auxiliary set datafiles

set newname for datafile 5 to new;

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

restore clone datafile 5;

switch clone datafile all;

}

executing Memory Script

executing command: SET until clause

executing command: SET NEWNAME

Starting restore at 29-JUN-18

allocated channel: ORA_AUX_DISK_1

channel ORA_AUX_DISK_1: SID=34 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 00005 to /data01/HCED_PITR_PCC/datafile/o1_mf_tbs_zyq_%u_.dbf

channel ORA_AUX_DISK_1: reading from backup piece /home/oracle/bak/db_01t6k254_1_1

channel ORA_AUX_DISK_1: piece handle=/home/oracle/bak/db_01t6k254_1_1 tag=TAG20180628T215236

channel ORA_AUX_DISK_1: restored backup piece 1

channel ORA_AUX_DISK_1: restore complete, elapsed time: 00:00:03

Finished restore at 29-JUN-18

datafile 5 switched to datafile copy

input datafile copy RECID=8 STAMP=980038478 file name=/data01/HCED_PITR_PCC/datafile/o1_mf_tbs_zyq_fmcsfttn_.dbf

contents of Memory Script:

{

# set requested point in time

set until time "to_date('2018-06-28 23:56:06','yyyy-mm-dd hh24:mi:ss')";

# online the datafiles restored or switched

sql clone "alter database datafile 5 online";

# recover and open resetlogs

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

alter clone database open resetlogs;

}

executing Memory Script

executing command: SET until clause

sql statement: alter database datafile 5 online

Starting recover at 29-JUN-18

using channel ORA_AUX_DISK_1

starting media recovery

archived log for thread 1 with sequence 3 is already on disk as file /u01/app/oracle/product/12.2.0.1/dbs/arch1_3_979872889.dbf

archived log for thread 1 with sequence 4 is already on disk as file /u01/app/oracle/product/12.2.0.1/dbs/arch1_4_979872889.dbf

archived log file name=/u01/app/oracle/product/12.2.0.1/dbs/arch1_3_979872889.dbf thread=1 sequence=3

archived log file name=/u01/app/oracle/product/12.2.0.1/dbs/arch1_4_979872889.dbf thread=1 sequence=4

media recovery complete, elapsed time: 00:00:01

Finished recover at 29-JUN-18

database opened

contents of Memory Script:

{

# create directory for datapump import

sql "create or replace directory TSPITR_DIROBJ_DPDIR as ''

/data01''";

# create directory for datapump export

sql clone "create or replace directory TSPITR_DIROBJ_DPDIR as ''

/data01''";

}

executing Memory Script

sql statement: create or replace directory TSPITR_DIROBJ_DPDIR as ''/data01''

Performing export of tables...

EXPDP> Starting "SYS"."TSPITR_EXP_hCed_Dhxe":

EXPDP> Processing object type TABLE_EXPORT/TABLE/TABLE_DATA

EXPDP> Processing object type TABLE_EXPORT/TABLE/STATISTICS/TABLE_STATISTICS

EXPDP> Processing object type TABLE_EXPORT/TABLE/STATISTICS/MARKER

EXPDP> Processing object type TABLE_EXPORT/TABLE/TABLE

EXPDP> . . exported "ZYQ"."T_RECOVER_TEST" 9.324 MB 72652 rows

EXPDP> Master table "SYS"."TSPITR_EXP_hCed_Dhxe" successfully loaded/unloaded

EXPDP> ******************************************************************************

EXPDP> Dump file set for SYS.TSPITR_EXP_hCed_Dhxe is:

EXPDP> /data01/tspitr_hCed_71393.dmp

EXPDP> Job "SYS"."TSPITR_EXP_hCed_Dhxe" successfully completed at Fri Jun 29 00:55:41 2018 elapsed 0 00:00:35

Export completed

contents of Memory Script:

{

# shutdown clone before import

shutdown clone abort

}

executing Memory Script

Oracle instance shut down

Performing import of tables...

IMPDP> Master table "SYS"."TSPITR_IMP_hCed_Arhm" successfully loaded/unloaded

IMPDP> Starting "SYS"."TSPITR_IMP_hCed_Arhm":

IMPDP> Processing object type TABLE_EXPORT/TABLE/TABLE

IMPDP> Processing object type TABLE_EXPORT/TABLE/TABLE_DATA

IMPDP> . . imported "ZYQ"."T_RECOVER_TEST_MAP" 9.324 MB 72652 rows

IMPDP> Processing object type TABLE_EXPORT/TABLE/STATISTICS/TABLE_STATISTICS

IMPDP> Processing object type TABLE_EXPORT/TABLE/STATISTICS/MARKER

IMPDP> Job "SYS"."TSPITR_IMP_hCed_Arhm" successfully completed at Fri Jun 29 00:56:43 2018 elapsed 0 00:00:45

Import completed

Removing automatic instance

Automatic instance removed

auxiliary instance file /data01/PCC/datafile/o1_mf_temp_fmcsd5ny_.tmp deleted

auxiliary instance file /data01/HCED_PITR_PCC/onlinelog/o1_mf_3_fmcsg3y6_.log deleted

auxiliary instance file /data01/HCED_PITR_PCC/onlinelog/o1_mf_2_fmcsg07o_.log deleted

auxiliary instance file /data01/HCED_PITR_PCC/onlinelog/o1_mf_1_fmcsfzr1_.log deleted

auxiliary instance file /data01/HCED_PITR_PCC/datafile/o1_mf_tbs_zyq_fmcsfttn_.dbf deleted

auxiliary instance file /data01/PCC/datafile/o1_mf_sysaux_fmcsc75c_.dbf deleted

auxiliary instance file /data01/PCC/datafile/o1_mf_undotbs1_fmcsc75h_.dbf deleted

auxiliary instance file /data01/PCC/datafile/o1_mf_system_fmcsc755_.dbf deleted

auxiliary instance file /data01/PCC/controlfile/o1_mf_fmcsc00p_.ctl deleted

auxiliary instance file tspitr_hCed_71393.dmp deleted

Finished recover at 29-JUN-18

RMAN>

驗證

SQL> select count(*) from T_RECOVER_TEST_MAP;

COUNT(*)

----------

72652

總結

（1）根據為恢復指定的時間點確定哪個備份包含需要恢復的表或表分割槽。

（2）確定目標主機上是否有足夠的空間來建立將在表或分割槽恢復過程中使用的輔助例項。如果所需空間不可用，則 RMAN 會顯示錯誤並退出恢復操作。

（3）在目標主機上建立一個輔助資料庫，並將指定的表或表分割槽恢復到此輔助資料庫中，直到指定的時間點。您可以指定恢復的資料檔案儲存在輔助資料庫中的目標主機上的位置。

（4）建立包含恢復的表或表分割槽的資料泵匯出轉儲檔案。您可以指定用於儲存恢復的表或表分割槽的後設資料的資料泵匯出轉儲檔案的名稱和位置。

（5）（可選）將 Data Pump 匯出轉儲檔案匯入到目標例項中。您可以選擇不將包含恢復的表或表分割槽的匯出轉儲檔案匯入目標資料庫。如果不將匯出轉儲檔案作為恢復過程的一部分匯入，則必須稍後使用“資料泵匯入”實用程式手動匯入它。

注：如果在匯入操作期間發生錯誤，RMAN 不會在表恢復結束時刪除匯出轉儲檔案。這使您能夠手動匯入轉儲檔案。

（6）（可選）重新命名目標資料庫中已恢復的表或表分割槽。您還可以將恢復的物件匯入到與最初存在的表空間或模式不同的表空間或模式中。12.2 開始，schema 可不同

注：當您使用 REMAP 選項時，不會匯入任何指定的約束和索引。這是為了避免與現有表格的名稱衝突。

如果不希望表被匯入，只需要恢復出 dmp 檔案，可以使用 notableimport 選項，命令如下：

RECOVER TABLE SCOTT.EMP, SCOTT.DEPT UNTIL TIME 'SYSDATE-1' AUXILIARY DESTINATION '/tmp/oracle/recover' DATAPUMP DESTINATION '/tmp/recover/dumpfiles' DUMP FILE 'emp_dept_exp_dump.dat' NOTABLEIMPORT;

如果需要將表恢復至另外的 schema，命令如下：

RECOVER TABLE HR.DEPARTMENTS, SH.CHANNELS

UNTIL TIME 'SYSDATE – 1' AUXILIARY DESTINATION '/tmp/auxdest'

REMAP TABLE hr.departments:example.new_departments, sh.channels:example.new_channels;

12c RMAN新特性之Recover Table

Recovering Tables and Table Partitions

建立測試表

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