| step |
log record |
| 1 |
begin(T1) |
| 2 |
update(T1, A, 5) |
| 3 |
begin(T2) |
| 4 |
update(T2, B, 10) |
| 5 |
start_checkpoint(T1, T2) |
| 6 |
update(T2, C, 15) |
| 7 |
begin(T3) |
| 8 |
update(T1, D, 20) |
| 9 |
commit(T1) |
| 10 |
update(T3, E, 25) |
| 11 |
commit(T2) |
| 12 |
end_checkpoint() |
| 13 |
update(T3, F, 30) |
|
CRASH |
|
|
- T1 committed, don't have to apply this undo.
|