多选题Which two statements are true regarding transactions in an Oracle database（）AMultiple transactions can use the same undo segment.BA transaction is assigned an undo segment when it is started.CMore than one transaction cannot share the same extent in th
题目
多选题
Which two statements are true regarding transactions in an Oracle database（）
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 tablespaceare used.