Fix the replay frontier
Fictional restored checkpoint includes sequences through 200. Recovery requires each next integer in order. Available logs 201,202,204,205;203 is absent. No skip rule is allowed and each sequence represents one operation in this drill.
| Sequence | Present | Applicable from 200 |
|---|---|---|
| 201 | Yes | Yes |
| 202 | Yes | Yes |
| 203 | No | Stop |
| 204–205 | Yes | Held beyond gap |
Check every next sequence
- Begin at 201
- Advance only one integer at a time
- Hold all records after the gap
A count of four files does not establish four replayable operations.
How many operations can be applied and what is the frontier?
Show the worked answer
Two operations,201 and 202; frontier 202. Two present operations 204/205 remain held.
Distinguish present from applicable
| Case | Decision | Reason |
|---|---|---|
| Apply 201 then 202 | Supported | No gap encountered |
| Apply 204 after 202 | Reject | 203 missing |
Locate 203 or obtain a separately specified reconstruction decision. Do not renumber 204 to hide the absence.