War Story: Ditching MongoDB 6 for PostgreSQL 17 Saved Our 50M User App from Data Inconsistencies

Our 50M user app was plagued by data inconsistencies due to MongoDB's eventual consistency model. We tried various fixes but nothing worked. We eventually migrated to PostgreSQL 17, which provided ACID compliance, JSONB flexibility, and performance gains. We successfully completed a 4-month migration with dual writes and backfill phases.