Example: Crash During Restart!

begin_checkpoint, end_checkpoint
update: T1 writes P5
update T2 writes P3
T1 abort
CLR: Undo T1 LSN 10, T1 End
update: T3 writes P1
update: T2 writes P5
CRASH, RESTART
CLR: Undo T2 LSN 60
CLR: Undo T3 LSN 50, T3 end
CRASH, RESTART
CLR: Undo T2 LSN 20, T2 end

LSN LOG

00,05
10
20
30
40,45
50
60

70
80,85

90

Xact Table
lastLSN
status
Dirty Page Table
recLSN
flushedLSN

ToUndo

undonextLSN

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