Detect fan-out before publishing account-level revenue totals
A new feature joins account tags to movement rows and inflates revenue for accounts with multiple tags.
- Focused work estimate
- 5h + prerequisites
- Priority in the scenario
- High
- Engineering practice
- Join cardinality · Data invariants
Estimated field mix
- Data engineering70%
- Quality engineering30%
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 SaaS analyst reports expansion revenue differently from finance because snapshots, refunds and contract changes are joined at incompatible grains.
Setup prerequisites
- Create a synthetic source schema and local transformation project.
- Use integer minor units and distinct reporting currencies.
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
- ADBT-101 · Declare the subscription-movement grain before joining invoice lines
- ADBT-102 · Separate recurring contract value from collected cash
- ADBT-104 · Join customer segments as of the revenue event date
- ADBT-103 · Reject source schema drift before materializing the mart
- ADBT-105 · Make incremental movement loads include revised source rows
- ADBT-106 · Represent cancelled subscriptions as movements instead of deleting them
Acceptance criteria
- Assert row and amount conservation across the join.
- Define tag allocation or a nonduplicating existence filter.
- Fail publication when conservation fails.
Implementation constraints
- Keep tag-level attribution distinct from account-level totals.
Verification to include
- Add two tags to an account and preserve its revenue total.
- Use the naive many-to-many join in a regression and detect inflation.
Deliverables
- Fan-out guard and corrected account model
Rollout and recovery
Canary the model in a separate schema; restore prior view selection on failed conservation.
Value of the work
For the engineer: Practice analytical modeling and explainable transformation contracts.
For the team: Review trustworthy reporting definitions and the cost of correcting historical reports.
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.