Versus
Postgres vs MongoDB
| Feature | PostgreSQL | MongoDB |
|---|---|---|
| Data Model | Relational (Tables/Rows). Excellent `jsonb` support. | Document (BSON). Schema-less collections. |
| Scaling | Primarily Vertical. Harder to shard (requires Citus/extensions). | Native Horizontal Sharding. Built to distribute across clusters. |
| Transactions | Rock-solid ACID guarantees across multiple tables by default. | Supports multi-document ACID (since v4), but comes with performance penalties. |
| Query Language | SQL. Universal, expressive, declarative. | MQL (Aggregation Pipeline). Powerful but vendor-specific and verbose. |
Choose Postgres If:
- You have clear, structured relationships (e.g., Users, Orders, Products).
- Data integrity is your top priority (foreign keys constraints).
- You want to use one database for relational data, JSON, and Geospatial (PostGIS).
Choose MongoDB If:
- Your data structure changes constantly and unpredictably.
- You are storing massive amounts of hierarchical data (e.g., IoT logs, catalog data).
- You absolutely must shard writes across multiple nodes immediately.