Represent key deletion as an ordered tombstone
Rebuilding the index resurrects deleted keys because deletion only changed memory. Append durable tombstones.
- Focused work estimate
- 2h + prerequisites
- Priority in the scenario
- Medium
- Engineering practice
- Log structure · State transitions
Estimated field mix
- Storage systems60%
- Database engineering40%
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.
- CKV-101 · Encode local key-value records with explicit length limits
- CKV-102 · Distinguish missing local keys from empty values
- CKV-103 · Build a local key-value index from validated log records
- CKV-104 · Declare local write acknowledgement after the durability barrier
- CKV-105 · Recover a torn key-value record at the end of the log
Acceptance criteria
- Deleted keys stay missing after restart
- Later puts can recreate key
- Tombstones obey acknowledgement rules
Implementation constraints
- Keep record ordering authoritative.
Verification to include
- Delete and restart
- Fail tombstone sync
Deliverables
- Tombstone format and restart cases
Rollout and recovery
Disable deletion if durable ordering is uncertain.
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.