053-373

Which of the following Oracle features utilize the undo tablespace? (Choose all that apply)
A. Flashback Query
B. Flashback Drop
C. Flashback Table
D. Flashback Database
E. Transaction Processing
F. Recycle Bin

　　Flashback Drop utilizes the Recycle Bin,which does not use the undo tablespace;Flashback Database  is a physical recovery method and does not use undo.

Transaction Processing 事务处理会在 undo 和 redo 产生数据。
flashback drop：利用 recyelebin 回收站原理
flashback table TEST10 to before drop [rename to test11];可以重命名
flashback query ，依赖 undo 数据，先查询，在做 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 依赖 undo 块
flashback table scott.test10 to scn 1952615
insert into test10 select * from scott.test10 as of scn 1952615;
flashback database DDL 语句，依赖闪回区的闪回日志
flashback database to timestamp to_timestamp('2013-09-23 15:09:52','yyyy-mm-dd hh24:mi:ss');时间减一秒。