Comparison mode
Same tools. Different reasons.
Compare domain constraints rather than copying an architecture from one product category to another.
Common architecture concepts
ExpertPostgreSQL + PostGIS
Food Delivery Platform
Coordinate customers, restaurants, couriers, menus, dispatch, and live delivery state.
Distinct concerns
Correctness boundary
- Order price snapshot
- Restaurant acceptance transition
- Single courier assignment
- Balanced settlement entries
Characteristic failures
- Menu changed: Item becomes unavailable after customer viewed it.
- Two couriers accept: Offers are accepted concurrently.
- Restaurant silent: Authorized order is not accepted before deadline.
At 1M+ scenario
Assign city/region ownership for dispatch and location streams; keep order/settlement invariants within a single writer boundary
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Ride Hailing Platform
Match riders and drivers under location churn and acceptance races.
Distinct concerns
Correctness boundary
- One trip-driver assignment
- Driver cannot hold incompatible active trips
- State ordering
- Fare and earnings
Characteristic failures
- Acceptance race: Two drivers accept near-simultaneously.
- Stale location: Nearest candidate is no longer nearby.
- Out-of-order GPS: Mobile batches arrive late.
At 1M+ scenario
Regional cells own matching and trips; event streams feed cross-region analytics without making them assignment authorities
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