[轉]開啓閃回以及閃回的四種原理

時間 2019-12-09

標籤開啓閃回以及四種原理简体版

原文原文鏈接

一、首先確認db_recovery_file_dest和db_recovery_file_dest_size 有值。

sys@TEST0910> show parameter recovery

NAME TYPE VALUE

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

db_recovery_file_dest string /u01/app/oracle/fast_recovery_ area

db_recovery_file_dest_size big integer 4122M

db_recovery_file_dest 放閃回日誌，默認路徑/u01/app/oracle/fast_recovery_ area

db_recovery_file_dest_size 存放閃回日誌空間的大小，默認4122M

二、開啓閃回

sys@TEST0910> shutdown immediate

Database closed.

Database dismounted.

ORACLE instance shut down.

sys@TEST0910> startup mount

ORACLE instance started.

Total System Global Area 2505338880 bytes

Fixed Size 2230952 bytes

Variable Size 587203928 bytes

Database Buffers 1895825408 bytes

Redo Buffers 20078592 bytes

Database mounted.

sys@TEST0910> alter database flashback on;

Database altered.

sys@TEST0910> alter database open;

Database altered.

三、查詢確認是否開啓閃回

sys@TEST0910> select name,flashback_on from v$database;

NAME FLASHBACK_ON

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

TEST0910 YES

閃回四種不一樣原理

flashback drop：利用recyelebin 回收站原理
flashback table TEST10 to before drop [rename to test11];能夠重命名

flashback query ，依賴undo數據，先查詢，在作insert
insert into test10 select * from test10 as of timestamp to_timestamp('2013-09-23 11:52:06','yyyy-mm-dd hh24:mi:ss');

flashback table 依賴undo塊
flashback table scott.test10 to scn 1952615
insert into test10 select * from scott.test10 as of scn 1952615;

flashback database DDL語句，依賴閃回區的閃回日誌
flashback database to timestamp to_timestamp('2013-09-23 15:09:52','yyyy-mm-dd hh24:mi:ss');時間減一秒。

閃迴歸檔--create as

來源：http://blog.csdn.net/rlhua/article/details/11934831sql

flashback drop實驗（sys用戶的除外，它沒有回收站）數據庫

一、查詢原來表的數量

sys@TEST0910> select count(*) from scott.test10;

COUNT(*)

----------

二、誤操做drop

sys@TEST0910> drop table scott.test10;

Table dropped.

三、登錄scoot用戶，查詢回收站

sys@TEST0910> conn scott/tiger

Connected.

scott@TEST0910> show recyclebin

ORIGINAL NAME RECYCLEBIN NAME OBJECT TYPE DROP TIME

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

TEST10 BIN$5w/YlwePKa7gQwEAAH+tZw==$0 TABLE 2013-09-23:11:40:56

四、查詢回收站裏的內容

scott@TEST0910> select * from "BIN$5w/YlwePKa7gQwEAAH+tZw==$0"; ------注意：此處是雙引號

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

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

14 rows selected.

五、兩種閃回方式

使用insert into TEST10 select * from "BIN$5w/YlwePKa7gQwEAAH+tZw==$0"; 閃回

使用flashback table閃回

scott@TEST0910> flashback table TEST10 to before drop [rename to test11];能夠重命名

Flashback complete.

scott@TEST0910> select count(*) from test10;

COUNT(*)

----------

flashback query實驗（基於undo數據）session

誤操做DML語句，剛剛發生，undo沒有被覆蓋

一、查詢原數據

11:52:06 scott@TEST0910> select count(*) from test10;

COUNT(*)

----------

11:52:06 這個時間點還有數據，稍後做爲參考

二、誤操做

11:52:19 scott@TEST0910> delete from test10;

14 rows deleted.

11:52:31 scott@TEST0910> commit;

Commit complete.

11:52:35 scott@TEST0910> select count(*) from test10;

COUNT(*)

----------

三、使用閃回查詢

11:54:25 scott@TEST0910> select * from test10 as of timestamp to_timestamp('2013-09-23 11:52:06','yyyy-mm-dd hh24:mi:ss');

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

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

14 rows selected.

四、插入閃回查詢的結果

11:54:44 scott@TEST0910> insert into test10 select * from test10 as of timestamp to_timestamp('2013-09-23 11:52:06','yyyy-mm-dd hh24:mi:ss');

14 rows created.

11:55:02 scott@TEST0910> commit;

Commit complete.

11:55:30 scott@TEST0910> select count(*) from test10;

COUNT(*)

----------

flashback table實驗（基於undo數據）oracle

一、查詢原數據

sys@TEST0910> select count(*) from test10;

COUNT(*)

----------

1 row selected.

二、查詢數據庫當前scn號，稍後做爲恢復參考

sys@TEST0910> select checkpoint_change# from v$database;

CHECKPOINT_CHANGE#

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

1952615

1 row selected.

三、誤操做

sys@TEST0910> delete from scott.test10;

14 rows deleted.

sys@TEST0910> commit;

Commit complete.

四、根據以前的scn號使用undo數據閃回查詢

sys@TEST0910> select * from scott.test10 as of scn 1952615;

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

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

14 rows selected.

五、將數據還原

能夠插入回去，如閃回查詢那樣：insert into test10 select * from scott.test10 as of scn 1952615;

另一種，能夠用閃回表的方式：flashback table scott.test10 to scn 1952615;

注意，閃回表時要開啓 row movement，否則要報錯。

sys@TEST0910> flashback table scott.test10 to scn 1952615;

flashback table scott.test10 to scn 1952615

ERROR at line 1:

ORA-08189: cannot flashback the table because row movement is not enabled

sys@TEST0910> alter table scott.test10 enable row movement;

Table altered.

sys@TEST0910> flashback table scott.test10 to scn 1952615;

Flashback complete.

sys@TEST0910> select count(*) from scott.test10;

COUNT(*)

----------

1 row selected.

flashback database實驗（使用lgmnr找出還原時間點）app

過程：激活日誌--刪數據--查日誌--logmnr--關庫--不用轉儲--mount--flashback數據庫（時間減一秒）--read only

開庫看正確與否--關庫--mount--開庫resetlogs

DDL語句的恢復：相似不徹底恢復，能夠恢復到某個時間點，依賴flashback log.

logmnr依賴的是redo和歸檔。

flashback database通常用於ddl操做，

dml用flashback query或flashback table。由於他們讀undo塊

ddl語句不生成undo塊

閃回數據庫有限制：好比解決不了media recovery等（硬盤壞了等）。仍是備份最重要。

一、使用logmnr來記錄時間點，首先必須設置有一下參數

show parameter utl; logmnr須要的路徑

sys@TEST0910> show parameter utl

NAME TYPE VALUE

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

create_stored_outlines string

utl_file_dir string /u01/app/oracle/utl

使用flashback database首先設置兩個參數：

db_recovery_file_dest string /u01/app/oracle/fast_recovery_area

db_recovery_file_dest_size big integer 4122M

sys@TEST0910> show parameter recovery

NAME TYPE VALUE

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

db_recovery_file_dest string /u01/app/oracle/fast_recovery_

area

db_recovery_file_dest_size big integer 4122M

並且須要alter database flashback on

ys@TEST0910> select name,flashback_on from v$database;

NAME FLASHBACK_ON

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

TEST0910 YES

1 row selected.

二、查詢原數據

sys@TEST0910> select count(*) from scott.test12;

COUNT(*)

----------

1 row selected.

3.激活logmnr，注意，必須有此步驟，否則logmnr出不來數據

sys@TEST0910> ALTER DATABASE ADD SUPPLEMENTAL LOG DATA;

Database altered.

四、誤操做DDL操做

sys@TEST0910> truncate table scott.test12;

Table truncated.

sys@TEST0910> select count(*) from scott.test12;

COUNT(*)

----------

1 row selected.

五、查詢當前日誌組和歸檔日誌

sys@TEST0910> select * from v$log;

GROUP# THREAD# SEQUENCE# BYTES BLOCKSIZE MEMBERS ARC STATUS FIRST_CHANGE# FIRST_TIME NEXT_CHANGE# NEXT_TIME

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

1 1 7 52428800 512 1 YES INACTIVE 1977009 2013-09-23 15:04:56 1981677 2013-09-23 15:05:11

2 1 8 52428800 512 1 YES ACTIVE 1981677 2013-09-23 15:05:11 1985831 2013-09-23 15:05:41

3 1 9 52428800 512 1 NO CURRENT 1985831 2013-09-23 15:05:41 2.8147E+14

3 rows selected.

sys@TEST0910> select * from v$logfile;

GROUP# STATUS TYPE MEMBER IS_

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

2 ONLINE /u01/app/oracle/oradata/test0910/redo02.log NO

1 ONLINE /u01/app/oracle/oradata/test0910/redo01.log NO

3 ONLINE /u01/app/oracle/oradata/test0910/redo03.log NO

3 rows selected.

sys@TEST0910> select name from v$archived_log;

NAME

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

/u01/app/oracle/fast_recovery_area/TEST0910/archivelog/2013_09_23/o1_mf_1_6_94146rg7_.arc

/u01/app/oracle/fast_recovery_area/TEST0910/archivelog/2013_09_23/o1_mf_1_7_941477xf_.arc

/u01/app/oracle/fast_recovery_area/TEST0910/archivelog/2013_09_23/o1_mf_1_8_941485th_.arc

61 rows selected.

六、執行logmnr

EXECUTE DBMS_LOGMNR_D.BUILD('dictionary.ora', -

'/u01/app/oracle/utl', -

DBMS_LOGMNR_D.STORE_IN_FLAT_FILE);

EXECUTE DBMS_LOGMNR.ADD_LOGFILE( -

LOGFILENAME => '/u01/app/oracle/oradata/test0910/redo03.log', -

OPTIONS => DBMS_LOGMNR.NEW);

EXECUTE DBMS_LOGMNR.ADD_LOGFILE( -

LOGFILENAME => '/u01/app/oracle/fast_recovery_area/TEST0910/archivelog/2013_09_23/o1_mf_1_6_94146rg7_.arc', -

OPTIONS => DBMS_LOGMNR.ADDFILE);

EXECUTE DBMS_LOGMNR.ADD_LOGFILE( -

LOGFILENAME => '/u01/app/oracle/fast_recovery_area/TEST0910/archivelog/2013_09_23/o1_mf_1_7_941477xf_.arc', -

OPTIONS => DBMS_LOGMNR.ADDFILE);

EXECUTE DBMS_LOGMNR.ADD_LOGFILE( -

LOGFILENAME => '/u01/app/oracle/fast_recovery_area/TEST0910/archivelog/2013_09_23/o1_mf_1_8_941485th_.arc', -

OPTIONS => DBMS_LOGMNR.ADDFILE);

EXECUTE DBMS_LOGMNR.START_LOGMNR( -

DICTFILENAME =>'/u01/app/oracle/utl/dictionary.ora',OPTIONS => -

DBMS_LOGMNR.DDL_DICT_TRACKING);

EXECUTE DBMS_LOGMNR.END_LOGMNR;

logminer官方參考： http://docs.oracle.com/cd/E11882_01/server.112/e22490/logminer.htm#i1009063

如下爲執行步驟

sys@TEST0910> EXECUTE DBMS_LOGMNR_D.BUILD('dictionary.ora', -

> '/u01/app/oracle/utl', -

> DBMS_LOGMNR_D.STORE_IN_FLAT_FILE);

LogMnr Dictionary Procedure started

LogMnr Dictionary File Opened

Procedure executed successfully - LogMnr Dictionary Created

PL/SQL procedure successfully completed.

sys@TEST0910> EXECUTE DBMS_LOGMNR.ADD_LOGFILE( -

> LOGFILENAME => '/u01/app/oracle/oradata/test0910/redo03.log', -

> OPTIONS => DBMS_LOGMNR.NEW);

PL/SQL procedure successfully completed.

sys@TEST0910> EXECUTE DBMS_LOGMNR.ADD_LOGFILE( -

> LOGFILENAME => '/u01/app/oracle/fast_recovery_area/TEST0910/archivelog/2013_09_23/o1_mf_1_8_941485th_.arc', -

> OPTIONS => DBMS_LOGMNR.ADDFILE);

PL/SQL procedure successfully completed.

sys@TEST0910> EXECUTE DBMS_LOGMNR.ADD_LOGFILE( -

> LOGFILENAME => '/u01/app/oracle/fast_recovery_area/TEST0910/archivelog/2013_09_23/o1_mf_1_7_941477xf_.arc', -

> OPTIONS => DBMS_LOGMNR.ADDFILE);

PL/SQL procedure successfully completed.

sys@TEST0910> EXECUTE DBMS_LOGMNR.ADD_LOGFILE( -

> LOGFILENAME => '/u01/app/oracle/fast_recovery_area/TEST0910/archivelog/2013_09_23/o1_mf_1_6_94146rg7_.arc', -

> OPTIONS => DBMS_LOGMNR.ADDFILE);

PL/SQL procedure successfully completed.

sys@TEST0910> EXECUTE DBMS_LOGMNR.START_LOGMNR( -

> DICTFILENAME =>'/u01/app/oracle/utl/dictionary.ora',OPTIONS => -

> DBMS_LOGMNR.DDL_DICT_TRACKING);

PL/SQL procedure successfully completed.

七、設置session時間格式

sys@TEST0910> alter session set nls_date_format='yyyy-mm-dd hh24:mi:ss';

Session altered.

八、查詢logmnr分析出的數據

sys@TEST0910> select username,scn,timestamp,sql_redo from v$logmnr_contents

2 where seg_name='TEST12';

USERNAME SCN TIMESTAMP SQL_REDO

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

SYS 1989009 2013-09-23 15:09:53 truncate table scott.test12;

sys@TEST0910> EXECUTE DBMS_LOGMNR.END_LOGMNR;

PL/SQL procedure successfully completed.

八、mount狀態下閃回

sys@TEST0910> shutdown immediate;

Database closed.

Database dismounted.

ORACLE instance shut down.

sys@TEST0910> startup mount;

ORACLE instance started.

Total System Global Area 2505338880 bytes

Fixed Size 2230952 bytes

Variable Size 587203928 bytes

Database Buffers 1895825408 bytes

Redo Buffers 20078592 bytes

Database mounted.

sys@TEST0910> flashback database to timestamp to_timestamp('2013-09-23 15:09:52','yyyy-mm-dd hh24:mi:ss');

此處注意，時間在logmnr查詢出的基礎上減1秒

Flashback complete.

九、讓數據庫置於read only，檢查數據是否正確恢復

sys@TEST0910> alter database open read only;

Database altered.

sys@TEST0910> select count(*) from scott.test12;

COUNT(*)

----------

1 row selected.

十、從新啓動數據庫，使用resetlogs打開數據庫

sys@TEST0910> shutdown immediate;

Database closed.

Database dismounted.

ORACLE instance shut down.

sys@TEST0910> startup mount;

ORACLE instance started.

Total System Global Area 2505338880 bytes

Fixed Size 2230952 bytes

Variable Size 587203928 bytes

Database Buffers 1895825408 bytes

Redo Buffers 20078592 bytes

Database mounted.

sys@TEST0910> alter database open

2 ;

alter database open

ERROR at line 1:

ORA-01589: must use RESETLOGS or NORESETLOGS option for database open

sys@TEST0910> alter database open resetlogs;

Database altered.

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