Verify a telemetry backfill against immutable aggregate snapshots
A conversion fix requires rebuilding a week of energy totals without obscuring what the previous dashboard showed.
- Focused work estimate
- 6h + prerequisites
- Priority in the scenario
- Medium
- Engineering practice
- Backfills · Data reconciliation
Estimated field mix
- Data engineering80%
- 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
A fictional energy dashboard receives hourly device batches. Corrupt archives and late corrections leave operators unsure which readings reached reports.
Setup prerequisites
- Create synthetic device batches and local object-store fixtures.
- Understand checksums and bounded streaming.
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
- AINGEST-101 · Record a manifest before decoding a telemetry batch
- AINGEST-102 · Cap decompressed telemetry bytes before archive expansion
- AINGEST-103 · Normalize sensor units through a versioned conversion table
- AINGEST-104 · Commit telemetry rows and the batch checkpoint atomically
- AINGEST-105 · Quarantine malformed readings with usable row coordinates
- AINGEST-106 · Apply corrected readings without overwriting source history
- AINGEST-107 · Use event-time watermarks without discarding late telemetry silently
- AINGEST-108 · Reconcile uploaded telemetry manifests against committed checkpoints
Acceptance criteria
- Build a new aggregate generation from named manifests.
- Compare counts, units and totals against frozen previous output.
- Atomically select the generation only after review.
Implementation constraints
- Use a synthetic seven-day corpus with declared correction cases.
Verification to include
- Backfill the corpus and reconcile every changed aggregate.
- Interrupt before activation and keep previous dashboard reads consistent.
Deliverables
- Backfill runner and generation difference report
Rollout and recovery
Activate one synthetic tenant; restore the old generation pointer on discrepancy.
Value of the work
For the engineer: Practice batch integrity, replay and data-quality boundaries.
For the team: Review whether operational data can be traced, corrected and recovered.
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.