We Migrated from MongoDB 7.0 to PostgreSQL 17: Handling 1B+ Documents Why We Migrated Our team maintains a large-scale social media analytics platform ingesting over 50M user activity events daily, totaling 1.2B documents stored in a sharded MongoDB 7.0 cluster. While MongoDB served us well for high-throughput writes and flexible schema needs early on, we hit critical limitations as our workload evolved: Complex cross-collection aggregations for billing and user attribution took 10+ seconds, impacting customer dashboards. Lack of native ACID transactions across shards led to data inconsistencies in billing workflows. Relational metadata (user profiles, subscription tiers) stored in separate collections required slow application-side joins. PostgreSQL 17’s upcoming features, including enhanced JSONB performance, declarative partitioning improvements, and MERGE statement optimizations, aligned with our long-term roadmap.…