Why I Migrated from MongoDB to PostgreSQL

I've used MongoDB since I started web development. The flexible schema, the JSON-like documents, the "just store whatever you want" philosophy — it all seemed perfect. Then came a ticketing platform that changed my mind.

The Problem with Documents for Relational Data

Building Pazimo, I had events, users, tickets, payments, venues, and organizers — all with complex relationships. MongoDB technically handles this, but the complexity grew fast. Aggregation pipelines for joins, inconsistent data due to lack of constraints, no easy transactions across collections.

What PostgreSQL Gets Right

Relations are first-class. Transactions are solid (ACID all the way). The query planner is incredibly smart. Foreign key constraints catch data integrity bugs at the database level. And with JSONB columns, you still get document storage when you genuinely need it.

The real revelation: SQL joins are not slow. Modern PostgreSQL with proper indexes handles joins on millions of rows in milliseconds. The "NoSQL is faster" argument only holds for specific write-heavy, schema-less use cases that most web apps don't have.

When MongoDB Still Makes Sense

MongoDB is still genuinely great for: highly nested documents with no need for joins, truly variable schemas where every document is different, and write-heavy workloads where you need horizontal sharding from day one.

For most web applications with related data? PostgreSQL. Choose based on your data shape, not industry trends.