各種資料庫閃回的總結

一、Fashback Query閃回查詢:Books-->APP-->Application Developer's Guide - Fundamentals-->Flashback

１、應用Flashback Query查詢過去的資料

select * from t1 as of scn 44545454;

select * from t1 as of timestamp to_timestamp('2012-09-28:09:20:13','yyyy-mm-dd:hh24:mi:SS');

select * from t1 as of timestamp sysdate-5/1440;

--select to_char(sysdate,'yyyy-mm-dd:hh24:mi:ss') sys_time,to_char(scn_to_timestamp(current_scn),'yyyy-mm-dd:hh24:mi:ss') scn_to_time,timestamp_to_scn(sysdate) date_to_scn,dbms_flashback.get_system_change_number scn1,current_scn scn2 from v$database;

２、應用Flashback Query查詢操作的事務

(1)使用Flashback Version Query 查詢記錄修改版本

select current_scn from v$database;
   DML操作........
    insert into t1 values(20,'gyj20');           

commit;

update t1 set name='gyj200000' where id=20;

delete from t1 where id=20;

select current_scn from v$database;
   SELECT ID,NAME,VERSIONS_STARTSCN STARTSCN,VERSIONS_ENDSCN ENDSCN,VERSIONS_OPERATION OPERATION,VERSIONS_XID XID
    FROM T1 VERSIONS BETWEEN SCN 2942841 AND 2942947;
--VERSIONS_STARTSCN:該條記錄操作時的SCN,如果為空,表示該行記錄是在查詢範圍外建立的
--VERSIONS_ENDSCN:該條記錄失效時的SCN,如果為空,說明記錄在這段時間無操作，或者已經被删數,配合VERSIONS_OPERATION
--VERSIONS_OPERATION:Ｉ表示insert、D表示delete、U表示update
--VERSIONS_XID:該操作的事務ID


           

(2)使用Flashback Transaction Query 查詢事務資訊(可以做審計)

　alter database add supplemental log data; //Oracle11g禁用了supplemental logging
   select current_scn from v$database;
    DML操作........
   select current_scn from v$database;
  select xid,commit_scn,commit_timestamp,operation,undo_sql
   from flashback_transaction_query q where q.xid in (select
   versions_xid from t1 versions between SCN  2943656 and 2943676);           

　SQL> DESC FLASHBACK_TRANSACTION_QUERY --能獲得這個事務執行時的很多資訊，包括UNDO語句

　Name Null? Type

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

　XID RAW(8)　　　 --事務ID,對應Versions Query中的VERSIONS_XID

　START_SCN NUMBER --事務開始時的SCN

　START_TIMESTAMP DATE --事務開始時間

　COMMIT_SCN NUMBER　　　 --事務送出時的SCN,該列為空的話，說明事務為活動事務

　COMMIT_TIMESTAMP DATE　　　　 --事務送出時間

　LOGON_USER VARCHAR2(30) --操作使用者

　UNDO_CHANGE# NUMBER　　　 --UNDO SCN

　OPERATION VARCHAR2(32) --執行操作，有幾個值:Delete、Insert、Update、B、UNKNOWN

　TABLE_NAME VARCHAR2(256)--DML操作對象的表名

　TABLE_OWNER VARCHAR2(32) --表的屬主

　ROW_ID VARCHAR2(19) --DML操作記錄的行位址

　UNDO_SQL VARCHAR2(4000)--撤銷該操作對應的SQL

二、Flashbackup Table閃回表:Books-->ADM-->Administrator's Guide-->flashback

1、從undo表空間恢複

select row_movement from user_tables where table_name='T1';
  alter table t1 enable row movement;
  select * from t1;
  select current_scn from v$database;
  delete from t1;
  commit;
  select * from t1;
  select * from t as of scn 9999;
  flashback table t1 to scn 9999;
  flashback table t1 to timestamp sysdate-5/1440;
  --create temporary tablespace temp2 tempfile '/u01/app/oracle/oradata/bxdb/temp02.dbf' size 50M;
  --alter user gyj  temporary tablespace temp2;


           

2、利用recyclebin,drop閃回

drop table t1;
  select object_name,original_name,droptime from recyclebin;
  flashback table t1 to before drop;
  --flashback table t1 to before drop rename to t1_old;           

實驗：多個名為t1的表恢複會是什麼順序???

　　　資源回收筒清除是按什麼規則的??????

恢複表時索引也同時被恢複，但索引名稱是????
drop table t1 purge; --真正删除表

           

三、資料庫閃回配置:Books-->BAK-->Backup and Recovery Advanced User's Guide-->flashback

　v$flashback_database_log

1、閃回區的大小

db_recovery_file_dest
  db_recovery_file_dest_size


           

2、閃回日志保留時間

db_flashback_retention_target
           

3、設閃回

startup mount
  alter database flashback on;
  alter database open;


           

４、閃回操作要在mount下做

一般在備庫中做完測試,用閃回恢複到測度前狀态
  flashbackup database TO TIMESTAMP(SYSDATE-1/24);
  alter database open;


           

５、建閃回點

create restore point 恢複點名字 [guarantee flashback database]
 drop restore point 恢複點名字
 flashback database to  restore point re_data;


           

6、*場景1:

show parameter db_recover
arcive log list;
select flashback_on,force_logging from v$database;
alter database force logging;
select dbms_flashback.get_system_change_number from dual;
drop table t1 purge;
shutdown immediate;
startup mount;
flashback database to  restore point re_data;           

--flashback database to scn 1511225;

alter database open resetlogs;
select * from t1;