1Z0-053 争议题目解析704

考试科目：1Z0-053
题库版本：V13.02

题库中原题为：

704.View the Exhibit and examine the data manipulation language (DML) operations that you performed
on the NEWEMP table. Note that the first two updated are not listed by the Flashback Versions Query.

What could be the reason?
A.The first two updated were not explicitly committed.
B.ALTER TABLE caused the recycle bin to release the space.
C.The data definition language (DDL) operation caused a log switch.
D.Flashback Versions Query stops producing versions of rows that existed before a change in the table
structure.
Answer:C

争议点：
网上有人说选择D，比如“标记为正确答案，不看answer版”题库。

比如：
LuiseDalian的解析：http://blog.itpub.net/17013648/viewspace-1349671/

C肯定不对，DDL操作并不会直接导致日志切换。
D选项：闪回版本查询不会显示在修改表结构操作之前的那些版本所对应的记录行。

初步结论：
保留争议，选择D。