Consider a transaction T1 that committed prior to checkpoint. The record appears in the log before the record. Any modifications made by T1 must have been written to the stable storage either with the checkpoint or prior to it. Thus at recovery time : ( choose all that apply )
A. There is a need to perform an undo operation on T1
B. There is a need to perform a redo operation on T1
C. There is no need to perform an undo operation on T1
D. There is no need to perform a redo operation on T1
Answer:A
Consider a transaction T1 that committed prior to checkpoint. The record appears in the log before the record. Any modifications made by T1 must have been written to the stable storage either with the checkpoint or prior to it. Thus at recovery time : ( choose all that apply )
A. There is a need to perform an undo operation on T1 B. There is a need to perform a redo operation on T1 C. There is no need to perform an undo operation on T1 D. There is no need to perform a redo operation on T1
Explanation: None.