Software Architecture11 min read
Building an On-Demand Service Platform: Calendars, Slots, & Payments
By Raghav Shah•
On-demand marketplaces require robust scheduling engines. A single double-booking ruins customer trust and wastes driver or helper dispatch time.
The complexity of real-time scheduling databases
Handling timezone conversions, helper local travel times, and locking slots during customer checkout sessions requires solid concurrent transaction isolation.
The Solution: Maid Agency Tech Architecture
We can implement a relational database model in PostgreSQL with transaction locks, preventing duplicate bookings of the same helper ID in overlapping time blocks.
PostgreSQL Safe Slot Reservation Query
-- Query to check and insert slot booking safely
BEGIN TRANSACTION;
SELECT * FROM bookings
WHERE helper_id = $1 AND start_time < $3 AND end_time > $2
FOR UPDATE;
-- If no rows match, insert the booking:
INSERT INTO bookings (helper_id, start_time, end_time, status)
VALUES ($1, $2, $3, 'confirmed');
COMMIT;Key Insights & Takeaways
- ✓ Relational databases ensure strict ACID transaction compliance
- ✓ Temporary Redis database locks prevent concurrent booking collisions
- ✓ Automated geolocation queries dispatch the nearest helper to cut travel times
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