PostgreSQL vs MongoDB: SQL vs NoSQL Showdown

Comprehensive comparison between the leading relational database and document database. Discover which approach fits your data model, scalability needs, and development workflow.

PostgreSQL

Relational + JSON

VS

MongoDB

Document Database

PostgreSQL vs MongoDB: Key Differences

Aspect PostgreSQL MongoDB
Data Model Relational + JSONB Document-based
Schema Structured (flexible with JSONB) Schema-less
Query Language SQL (standard) MongoDB Query Language
ACID Compliance Full ACID ACID (with limitations)
Joins Native SQL joins Limited ($lookup)
Horizontal Scaling Requires extensions Built-in sharding
JSON Support Native JSONB Native BSON

When to Choose PostgreSQL vs MongoDB

Choose PostgreSQL When:

  • Complex relationships between data entities
  • ACID compliance is non-negotiable
  • Advanced SQL queries and analytics
  • Data integrity and consistency critical
  • Existing SQL expertise in team
  • Hybrid relational/document requirements
  • Financial or transactional applications
  • Reporting and business intelligence

Choose MongoDB When:

  • Flexible, evolving data schemas
  • Document-centric data model
  • Horizontal scaling requirements
  • Rapid development and prototyping
  • Content management systems
  • Real-time applications
  • IoT and sensor data collection
  • Agile development methodologies

PostgreSQL vs MongoDB: Frequently Asked Questions

Can PostgreSQL replace MongoDB for document storage?

Yes, PostgreSQL's JSONB support makes it an excellent choice for document storage while maintaining relational capabilities. JSONB offers indexing, operators, and performance comparable to MongoDB for many document-based use cases.

Which is better for microservices: PostgreSQL or MongoDB?

Both can work well for microservices. MongoDB's schema flexibility and horizontal scaling suit services with evolving data models. PostgreSQL works well when services need complex queries, transactions, or hybrid relational/document storage.

Is MongoDB faster than PostgreSQL?

Performance depends on the use case. MongoDB typically performs better for simple document operations and horizontal scaling scenarios. PostgreSQL excels in complex queries, joins, and analytical workloads. Both can achieve excellent performance with proper optimization.

Which database is easier to scale horizontally?

MongoDB has built-in horizontal scaling with automatic sharding, making it easier to scale out-of-the-box. PostgreSQL requires extensions like Citus or third-party solutions for horizontal scaling, but offers more control over the scaling strategy.

Can I use SQL with MongoDB?

MongoDB has limited SQL support through MongoDB Connector for BI and some third-party tools, but it's not native. PostgreSQL offers full SQL support plus JSON operations, making it better for teams preferring SQL.

Which database has better ACID compliance?

PostgreSQL has mature, full ACID compliance across all operations. MongoDB added multi-document ACID transactions in version 4.0, but with some limitations and performance considerations compared to PostgreSQL's implementation.