Oracle OCP 1Z0 053 Q143(Flashback Data Archive)

143.Which two are the prerequisites to enable Flashback Data Archive? (Choose two.)
A. Database must be running in archivelog mode.
B. Automatic undo management must be enabled.
C. Undo retention guarantee must be enabled.
D. The tablespace on which the Flashback Data Archive is created must be managed with Automatic
Segment Space Management (ASSM).
Answer: BD

參考：https://docs.oracle.com/cd/B28359_01/server.111/b28286/statements_5009.htm
       http://docs.oracle.com/cd/E11882_01/appdev.112/e41502/adfns_flashback.htm#ADFNS01001
        http://blog.csdn.net/rlhua/article/details/13503997

Oracle Flashback features use the Automatic Undo Management (AUM) system to obtain metadata and historical data for transactions. They rely on undo data, which are records of the effects of individual transactions. For example, if a user runs an UPDATE statement to change a salary from 1000 to 1100, then Oracle Database stores the value 1000 in the undo data.

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