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

90,95

Xact Table

lastLSN

status

Dirty Page Table

recLSN

flushedLSN

ToUndo

undonextLSN

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