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