Reference no: EM13509444

The description in Section 18.6.1 of the Analysis phase made the sim-plifying assumption that no log records appeared between the begin checkpoint and end checkpoint records for the most recent complete checkpoint. The following ques-tions explore how such records should be handled. 

1. Explain why log records could be written between the begin checkpoint and end checkpoint records.

2. Describe how the Analysis phase could be modi?ed to handle such records.

3. Consider the execution shown in Figure 18.4. Show the contents of the end checkpoint record.

4. Illustrate your modi?ed Analysis phase on the execution shown in Figure 18.4. 

LSN                     LOG

00                    begin_checkpoint 

10                    update: T1 writes P1 

20                    T1 commit 

30                    update: T2 writes P2 

40                    T1 end 

50                    T2 abort 

60                    update: T3 writes P3 

70                    end_checkpoint 

80                    T3 commit 

CRASH, RESTART 

figure: Log Records between Checkpoint Records