19. Flashback Data Archive
• 前面介绍的闪回技术在时间上都有一定的限制(通常不会太长), 归档闪回则可以设置为闪回到过去的任意时间. 下
面使用示例进行演示:
– 创建用于归档闪回的表空间, 该表空间用于存放支持归档闪回表的历史数据
create tablespace fda datafile 'fda1.dbf' size 10m;
– 在该表空间中创建闪回归档, 指定存留时间为7Y
create flashback archive fla1 tablespace fda retention 7 year;
– 创建相应的用户并授予权限
grant dba to fbdauser identified by fbdauser;
grant flashback archive on fla1 to fbdauser;
– 登录该用户创建表并设置归档闪回
connect fbdauser/fbdauser
create table t1 as select * from all_users;
alter table t1 flashback archive fla1;
– 查询FDA表空间, 相应的段被创建, 该段包含了被保护对象的历史数据
select segment_name,segment_type from dba_segments where tablespace_name='FDA';
– 实例归档查询
delete from t1;
commit;
select count(*) from t1;
select count(*) from t1 as of timestamp(sysdate - 2/1440);
– as SYSDBA
alter table fbdauser.t1 no flashback archive;
drop user fbdauser cascade;
drop tablespace fda including contents and datafiles;
drop flashback archive fla1;