Oracle Study之案例--数据恢复神器Flashback（3）
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2023-05-11 09:01:55
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Oracle Study之案例--数据恢复神器Flashback（3）
Flashback Database：
案例分析：
flashback database：利用flashback log 对整个database 做回退到过去的某个时间点（用于DDL 的误操作如drop 和 truncate），类似于RMAN的不完全恢复（media recovery incompelete）
因为flashback database是不完全恢复，在恢复到过去的时间点前应该对数据库备份！
1、查看flashback database是否开启
07:21:27 SQL> select flashback_on from v$database;
FLASHBACK_ON
------------------
NO
2、创建recovery area
07:21:33 SQL> show parameter recover
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
db_recovery_file_dest string /u01/app/oracle/flash_recovery
_area
db_recovery_file_dest_size big integer 2G
recovery_parallelism integer 2 ---recovery area可以存储flashback log、archive log、rman backup等
[oracle@work ~]$ mkdir -p /disk1/recovery/prod
配置recovery area：
07:22:49 SQL> alter system set db_recovery_file_dest='/disk1/recovery/prod' scope=spfile;
System altered.
在归档模式下启用flashback database：
07:25:06 SQL> alter database flashback on;
Database altered.
07:25:29 SQL> select flashback_on from v$database;
FLASHBACK_ON
------------------
YES
07:25:38 SQL> alter database open;
Database altered.
案例1：flashback database恢复DDL误操作（基于SCN)
flashback database可以用于基于时间点或SCN的数据恢复（可以通过logminer来查看DDL操作的时间点）
1)模拟环境
15:18:17 SYS@ test1 >select current_scn from v$database;
CURRENT_SCN
-----------
1264788
07:26:30 SQL> select * from test;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
7369 SMITH CLERK 7902 17-DEC-80 800 20
7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 30
7369 SMITH CLERK 7902 17-DEC-80 800 20
7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 30
7521 WARD SALESMAN 7698 22-FEB-81 1250 500 30
7566 JONES MANAGER 7839 02-APR-81 2975 20
7654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400 30
7698 BLAKE MANAGER 7839 01-MAY-81 2850 30
7782 CLARK MANAGER 7839 09-JUN-81 2450 10
7788 SCOTT ANALYST 7566 19-APR-87 3000 20
7839 KING PRESIDENT 17-NOV-81 5000 10
7844 TURNER SALESMAN 7698 08-SEP-81 1500 0 30
7876 ADAMS CLERK 7788 23-MAY-87 1100 20
7900 JAMES CLERK 7698 03-DEC-81 950 30
7902 FORD ANALYST 7566 03-DEC-81 3000 20
7934 MILLER CLERK 7782 23-JAN-82 1300 10
16 rows selected.
07:26:36 SQL> drop table test purge;
Table dropped.
07:27:20 SQL> create table test as select * from emp where rownum=1;
Table created.
07:27:25 SQL> select * from test;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
7369 SMITH CLERK 7902 17-DEC-80 800 20
查看flashback 日志：
[oracle@work ~]$ ls /disk1/recovery/prod/PROD/flashback/
o1_mf_74q999lb_.flb
关闭数据库后，在mount状态下恢复：
07:29:22 SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
07:29:53 SQL> startup mount
ORACLE instance started.
Total System Global Area 314572800 bytes
Fixed Size 1219184 bytes
Variable Size 71304592 bytes
Database Buffers 239075328 bytes
Redo Buffers 2973696 bytes
Database mounted.
通过flashback database将库恢复到过去的scn：
07:30:02 SQL> flashback database to scn 1264788;
Flashback complete.
将database以read only方式打开，先验证下恢复是否成功，如果不成功，再从新进入mount下恢复
07:31:29 SQL> alter database open read only;
Database altered.
07:31:34 SQL> select * from scott.test;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
7369 SMITH CLERK 7902 17-DEC-80 800 20
7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 30
7369 SMITH CLERK 7902 17-DEC-80 800 20
7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 30
7521 WARD SALESMAN 7698 22-FEB-81 1250 500 30
7566 JONES MANAGER 7839 02-APR-81 2975 20
7654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400 30
7698 BLAKE MANAGER 7839 01-MAY-81 2850 30
7782 CLARK MANAGER 7839 09-JUN-81 2450 10
7788 SCOTT ANALYST 7566 19-APR-87 3000 20
7839 KING PRESIDENT 17-NOV-81 5000 10
7844 TURNER SALESMAN 7698 08-SEP-81 1500 0 30
7876 ADAMS CLERK 7788 23-MAY-87 1100 20
7900 JAMES CLERK 7698 03-DEC-81 950 30
7902 FORD ANALYST 7566 03-DEC-81 3000 20
7934 MILLER CLERK 7782 23-JAN-82 1300 10
16 rows selected.
--恢复成功，重新以resetlogs的方式open database
07:31:40 SQL> shutdown immedaite
SP2-0717: illegal SHUTDOWN option
07:31:45 SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
07:32:02 SQL> startup mount
ORACLE instance started.
Total System Global Area 314572800 bytes
Fixed Size 1219184 bytes
Variable Size 71304592 bytes
Database Buffers 239075328 bytes
Redo Buffers 2973696 bytes
Database mounted.
07:32:10 SQL> alter database open resetlogs;
Database altered.
验证：
07:32:25 SQL> select * from scott.test;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
7369 SMITH CLERK 7902 17-DEC-80 800 20
7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 30
7369 SMITH CLERK 7902 17-DEC-80 800 20
7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 30
7521 WARD SALESMAN 7698 22-FEB-81 1250 500 30
7566 JONES MANAGER 7839 02-APR-81 2975 20
7654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400 30
7698 BLAKE MANAGER 7839 01-MAY-81 2850 30
7782 CLARK MANAGER 7839 09-JUN-81 2450 10
7788 SCOTT ANALYST 7566 19-APR-87 3000 20
7839 KING PRESIDENT 17-NOV-81 5000 10
7844 TURNER SALESMAN 7698 08-SEP-81 1500 0 30
7876 ADAMS CLERK 7788 23-MAY-87 1100 20
7900 JAMES CLERK 7698 03-DEC-81 950 30
7902 FORD ANALYST 7566 03-DEC-81 3000 20
7934 MILLER CLERK 7782 23-JAN-82 1300 10
16 rows selected.
因为flashback database是不完全恢复，在恢复到过去的时间点前应该对数据库备份！
案例2：基于timestamp的flashback database
04:04:28 SQL> show user;
USER is "SYS"
04:08:04 SQL> conn scott/tiger
Connected.
04:08:13 SQL> select to_char(sysdate,'yyyy-mm-dd hh34:mi:ss') from dual;
TO_CHAR(SYSDATE,'YY
-------------------
2011-03-18 04:08:42
04:09:02 SQL> conn /as sysdba
Connected.
04:09:07 SQL> select current_scn from v$database;
CURRENT_SCN
-----------
1437597
04:09:10 SQL> conn scott/tiger
Connected.
04:09:29 SQL> select * from tab;
TNAME TABTYPE CLUSTERID
------------------------------ ------- ----------
EMP TABLE
DEPT TABLE
BONUS TABLE
SALGRADE TABLE
QUEST_SL_TEMP_EXPLAIN1 TABLE
EMP1 TABLE
ERRLOG TABLE
PART_SALES TABLE
T01 TABLE
DEPT1 TABLE
10 rows selected.
select * from t01;
ID NA
---------- --
1 TM
04:10:07 SQL> insert into t01 values(2,'aa');
1 row created.
04:10:17 SQL> insert into t01 values(3,'bb');
1 row created.
04:10:26 SQL> commit;
Commit complete.
04:10:30 SQL> drop table t01;
Table dropped.
04:10:59 SQL> conn /as sysdba
Connected.
04:11:03 SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
04:11:28 SQL> startup mount
ORACLE instance started.
Total System Global Area 314572800 bytes
Fixed Size 1219184 bytes
Variable Size 184550800 bytes
Database Buffers 125829120 bytes
Redo Buffers 2973696 bytes
Database mounted.
将database恢复到过去的时间点：
04:12:07 SQL> flashback database to timestamp to_timestamp('2011-03-18 04:10:26','yyyy-mm-dd hh34:mi:ss');
Flashback complete.
04:13:34 SQL> alter database open;
alter database open
*
ERROR at line 1:
ORA-01589: must use RESETLOGS or NORESETLOGS option for database open
04:14:10 SQL> alter database open noresetlogs;
alter database open noresetlogs
*
ERROR at line 1:
ORA-01610: recovery using the BACKUP CONTROLFILE option must be done
04:14:18 SQL> alter database open resetlogs;
Database altered.
04:15:35 SQL> select * from v$log;
GROUP# THREAD# SEQUENCE# BYTES MEMBERS ARC STATUS FIRST_CHANGE# FIRST_TIME
---------- ---------- ---------- ---------- ---------- --- ---------------- ------------- -------------------
1 1 0 52428800 2 YES UNUSED 0
2 1 0 52428800 2 YES UNUSED 0
3 1 0 52428800 2 YES UNUSED 0
4 1 0 52428800 2 YES UNUSED 0
5 1 0 52428800 2 YES UNUSED 0
6 1 1 52428800 2 NO CURRENT 1437637 2011-03-18 04:14:27
6 rows selected.
04:15:59 SQL> conn scott/tiger
Connected.
04:16:18 SQL> select * from t01;
ID NA
---------- --
1 TM
04:34:35 SQL> desc v$flashback_database_log;
Name Null? Type
----------------------------------------------------------------------------------- -------- - OLDEST_FLASHBACK_SCN NUMBER
OLDEST_FLASHBACK_TIME DATE
RETENTION_TARGET NUMBER
FLASHBACK_SIZE NUMBER
ESTIMATED_FLASHBACK_SIZE NUMBER
04:34:37 SQL> select * from v$flashback_database_log;
OLDEST_FLASHBACK_SCN OLDEST_FLASHBACK_TI RETENTION_TARGET FLASHBACK_SIZE TIMATED_FLASHBACK_SIZE
-------------------- ------------------- ---------------- -------------- ----------------------
1436931 2011-03-18 03:51:43 1440 8192000 115703808[oracle@rh7 ~]$ sqlplus '/as sysdba' SQL*Plus: Release 11.2.0.1.0 Production on Thu Jan 15 11:38:34 2015 Copyright (c) 1982, 2009, Oracle. All rights reserved. Connected to an idle instance. 11:41:52 SYS@ test1 >select name,FLASHBACK_ON from v$database; NAME FLASHBACK_ON --------- ------------------ TEST1 YES Elapsed: 00:00:00.00 11:38:34 SYS@ test1 >startup ORACLE instance started. Total System Global Area 523108352 bytes Fixed Size 1337632 bytes Variable Size 188745440 bytes Database Buffers 327155712 bytes Redo Buffers 5869568 bytes Database mounted. Database opened. --下面查看闪回区分配的大小为大约M，闪回分钟以内的数据则需要M左右的空间 --注意列oldest_flashback_time说明了允许返回的最早的时间点 11:39:17 SYS@ test1 >select oldest_flashback_scn old_flhbck_scn,oldest_flashback_time old_flhbck_tim, 11:39:37 2 retention_target rete_trgt,flashback_size/1024/1024 flhbck_siz, 11:39:47 3 estimated_flashback_size/1024/1024 est_flhbck_size 11:40:01 4 from v$flashback_database_log; OLD_FLHBCK_SCN OLD_FLHBCK_T RETE_TRGT FLHBCK_SIZ EST_FLHBCK_SIZE -------------- ------------ ---------- ---------- --------------- 11898580 10-JAN-15 1440 305.429688 266.601563 --查看闪回 11:40:15 SYS@ test1 >select * from v$flashback_database_stat; BEGIN_TIME END_TIME FLASHBACK_DATA DB_DATA REDO_DATA ESTIMATED_FLASHBACK_SIZE ------------ ------------ -------------- ---------- ---------- ------------------------ 15-JAN-15 15-JAN-15 573440 24576 109056 0 --查看sga中分配的闪回空间大小 11:40:45 SYS@ test1 >select * from v$sgastat where name like 'flashback%'; POOL NAME BYTES ------------ -------------------------- ---------- shared pool flashback generation buff 4149140 shared pool flashback_marker_cache_si 9196
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