各种数据库闪回的总结

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

１、应用Flashback Query查询过去的数据

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、应用Flashback Query查询操作的事务

(1)使用Flashback Version Query 查询记录修改版本

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:该条记录操作时的SCN,如果为空,表示该行记录是在查询范围外创建的
--VERSIONS_ENDSCN:该条记录失效时的SCN,如果为空,说明记录在这段时间无操作，或者已经被删数,配合VERSIONS_OPERATION
--VERSIONS_OPERATION:Ｉ表示insert、D表示delete、U表示update
--VERSIONS_XID:该操作的事务ID


           

(2)使用Flashback Transaction Query 查询事务信息(可以做审计)

　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 --能获得这个事务执行时的很多信息，包括UNDO语句

　Name Null? Type

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

　XID RAW(8)　　　 --事务ID,对应Versions Query中的VERSIONS_XID

　START_SCN NUMBER --事务开始时的SCN

　START_TIMESTAMP DATE --事务开始时间

　COMMIT_SCN NUMBER　　　 --事务提交时的SCN,该列为空的话，说明事务为活动事务

　COMMIT_TIMESTAMP DATE　　　　 --事务提交时间

　LOGON_USER VARCHAR2(30) --操作用户

　UNDO_CHANGE# NUMBER　　　 --UNDO SCN

　OPERATION VARCHAR2(32) --执行操作，有几个值:Delete、Insert、Update、B、UNKNOWN

　TABLE_NAME VARCHAR2(256)--DML操作对象的表名

　TABLE_OWNER VARCHAR2(32) --表的属主

　ROW_ID VARCHAR2(19) --DML操作记录的行地址

　UNDO_SQL VARCHAR2(4000)--撤销该操作对应的SQL

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

1、从undo表空间恢复

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闪回

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;           

实验：多个名为t1的表恢复会是什么顺序???

　　　回收站清除是按什么规则的??????

恢复表时索引也同时被恢复，但索引名称是????
drop table t1 purge; --真正删除表

           

三、数据库闪回配置:Books-->BAK-->Backup and Recovery Advanced User's Guide-->flashback

　v$flashback_database_log

1、闪回区的大小

db_recovery_file_dest
  db_recovery_file_dest_size


           

2、闪回日志保留时间

db_flashback_retention_target
           

3、设闪回

startup mount
  alter database flashback on;
  alter database open;


           

４、闪回操作要在mount下做

一般在备库中做完测试,用闪回恢复到测度前状态
  flashbackup database TO TIMESTAMP(SYSDATE-1/24);
  alter database open;


           

５、建闪回点

create restore point 恢复点名字 [guarantee flashback database]
 drop restore point 恢复点名字
 flashback database to  restore point re_data;


           

6、*场景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;