45题、choose three
Which three statements are true about the purpose of checkpoints?
A) They ensure that instance recovery starts in the event of an instance failure.
B) They ensure that dirty buffers in the buffer cache are written to disk regularly.
C) They reduce the time required for recovery in case of an instance failure.
D) They ensure that all the dirty buffers are written to disk during a normal shutdown.
E) They ensure that uncommitted transactions are rolled back in case of an instance failure.
Answer：BCD
(解析：checkpoint进程就是给dbwr写的信号，定期的保持，减少实例恢复时间，正常关闭时把所有的脏块写入数据文件。来自3组：1015267481)