(Review) The Log File
Needs to be on "stable storage"
Contains:
- Transaction starts/stops
- DB writes: "before" and "after" images
- befores can be used to rollback an aborted transaction
- afters can be used to redo a transaction without reexecuting it
- COMMITs and ABORTs
The log itself is as critical as the DB!
Reliable backups are critical, too!