I considered event sourcing for SlotTurf's payment flow. Here's why I didn't use it.

Index strategies, query optimization, and EXPLAIN ANALYZE patterns. Study notes, not a production war story.

Two users booked the same turf slot at the same time. Here's what was happening at the database level and how SELECT FOR UPDATE fixed it.

Turf booking platform for local sports venues Next.js frontend, Go/Gin REST API deployed on GCP Cloud Run, PostgreSQL via Supabase.