Logging Undo’s (cont’d)
- Multi-page updates (it’s best to avoid them)
- Restart grows the log by logging undos. Each time it crashes, it has more log to process
Optimization - CLR points to the transaction’s log record preceding the corresponding “do”.
- Splices out undone work
- Avoids undoing undone work during abort
- Avoids growing the log due to aborts during Restart