閃回
（使用UNDO表空間）
恢復最近刪除的、
flashback table emp1 to before drop ;
清除最先刪除的、
purge table emp1 ;
閃回查詢
select * from scott.emp1 as of scn 966132;
閃迴歸檔
創建表空間
create tablespace zzz datafile ‘/u01/data/orcl/fda01.dbf’ size 5m;
設置表空間爲閃迴歸檔
create flashback archive fla tablespace zzz quota 2m retention 2 year;
授權給用戶
grant flashback archive on fla to scott;
設置表爲閃迴歸檔
alter table scott.z1 flashback archive fla;
退出閃迴歸檔 可以刪除表
alter table scott.z1 no flashback archive;
沒有表後可刪除閃迴歸檔
drop flashback archive fla;
閃回表
打開行移動
alter table scott.emp1 enable row movement;
將表回退到之前的狀態
flashback table scott.emp1 to scn 975172;
閃回版本查詢
查詢一段時間內表的操作
select versions_startscn, versions_endscn, versions_xid, versions_operation,id,name from scott.t3 versions between scn minvalue and maxvalue;
閃回事務查詢
需先執行
ALTER DATABASE ADD SUPPLEMENTAL LOG DATA (ALL) COLUMNS;
desc flashback_transaction_query;
根據事務號查詢
select undo_sql from flashback_transaction_query where xid=hextoraw(‘versions_xid’);
閃回數據庫
mount狀態下 開啓歸檔
STARTUP MOUNT ;
show parameter recovery_file;
設置閃回日誌大小
alter system set db_recovery_file_dest_size=2g;
指定閃回日誌目錄
alter system set db_recovery_file_dest=’/flashback’;
閃回日誌默認存放24小時
show parameter flash;
開啓閃回
alter database flashback on;
undo
屬性
show parameter undo
創建
create undo tablespace undotbs2 datafile ‘/u01/data/orcl/undotbs02.dbf’ size 50M autoextend on ;
切換
alter system set undo_tablespace=undotbs2;