Recover a torn key-value record at the end of the log
A crash leaves a partial final record and startup refuses every key. Recover the valid prefix conservatively.
- Focused work estimate
- 3h + prerequisites
- Priority in the scenario
- High
- Engineering practice
- Crash recovery · Integrity
Estimated field mix
- Storage systems80%
- Database engineering20%
Field percentages are editorial estimates of the ticket's engineering focus. They total 100%; they are not measured time, proficiency scores, or ownership evidence.
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Project context
Fictional desktop cache Pebble needs a small embedded key-value engine. Build against generated keys and bytes using an ordinary filesystem adapter; no production database replacement is implied.
Setup prerequisites
- Create a disposable local fixture directory.
- Implement fault injection for partial writes, sync failure and process restart.
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
Acceptance criteria
- Valid prefix remains readable
- Incomplete tail is identified
- Middle corruption fails closed
Implementation constraints
- Tail truncation requires an explicit recovery mode.
Verification to include
- Recover partial final record
- Corrupt middle record
Deliverables
- Tail recovery and corruption cases
Rollout and recovery
Preserve original log before applying tail repair.
Value of the work
For the engineer: Practice storage formats, durability boundaries and corruption handling.
For the team: Inspect whether an engineer can state and test persistence guarantees.
Evidence boundaries
Outcome Evidence: Tests, patches, and runbooks are requested deliverables. They become Outcome Evidence only through a qualified Mission and immutable Evidence IDs.
Ownership Evidence: Independent adaptation must be observed under a declared verification policy and cite immutable Evidence IDs. Completing a planning ticket establishes no Ownership Evidence.