Use keyset traversal for shipments sharing timestamps
Pagination drops shipments when several rows have the same update timestamp.
- Focused work estimate
- 3h + prerequisites
- Priority in the scenario
- High
- Engineering practice
- Database queries
Estimated field mix
- Database engineering70%
- API design30%
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 logistics platform lists shipments for partner dashboards. Offset pagination duplicates records during updates, while unrestricted filters create expensive database queries.
Setup prerequisites
- Create a local shipment dataset with synthetic tenants, equal timestamps, and concurrent update fixtures.
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
Acceptance criteria
- Compare the complete sort tuple.
- Use the unique tie-breaker consistently in both directions.
- Avoid duplicate boundary rows.
Implementation constraints
- Indexes must match the declared ordering.
Verification to include
- Traverse a fixture with many equal timestamps.
- Verify no omission or duplication at page boundaries.
Deliverables
- Keyset query implementation.
Rollout and recovery
Compare full traversal against a fixed fixture before replacing offsets.
Value of the work
For the engineer: Practice cursor design, query contracts, and consistency/performance tradeoffs.
For the team: Provide predictable list APIs that remain bounded and preserve tenant scope.
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.