OCP考试052考题：1Z0-V8.02-第27题

OCP考试052考题：1Z0-V8.02-第27题，完整题库请点击这里联系老师咨询了解

27. Which two statements are true regarding transactions in an Oracle database? (Choose two.)

A.Multiple transactions can use the same undo segment.

B.A transaction is assigned an undo segment when it is started.

C.More than one transaction cannot share the same extent in the undo tablespace.

D.The transactions use system undo segment to store undo data if all the segments in the undo

tablespace are used.

Answer: AB

答案解析：

A答案：多个事务可以共享同一个undo段

B答案：事务处理开始时就会分配还原段。

C答案：多个事务可以共享同一个undo段，段包括区，即也可以共享同一个区。

D答案：在undo表空间所有的段都填满后，事务处理会自动转回到第一个区或请求为还原段分配新区。如果不能分配新区，则有可能覆盖原来的undo数据，或者报错。