Undo Logging (cont)
Simplified view of recovery using UNDO logging:
- scan backwards through log
- if
<COMMIT T>, mark T as committed
- if
<T,X,v> and T not committed, set X to v on disk
- if
<START T> and T not committed, put <ABORT T> in log
Assumes we scan entire log; use checkpoints to limit scan.
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