PostgreSQL vs Redis for Solo Developers

Quick Comparison

PostgreSQL Overview

PostgreSQL is the relational database I reach for on every production project. It handles structured data with rock-solid reliability, supports JSONB for flexible documents, has built-in full-text search, and an extension ecosystem that covers everything from geospatial queries to time-series data. You get the power of five different databases in one.

For a solo developer, Postgres is the foundation you build everything on. It stores your users, orders, content, analytics, and anything else that needs to persist reliably. Every modern hosting platform (Supabase, Neon, Railway, Render) offers managed Postgres, so you never have to worry about backups or replication yourself.

The learning curve is moderate, but the investment pays off fast. Once you understand indexes, JSONB, and basic query optimization, you can build applications that scale well beyond what a solo developer typically needs.

Redis Overview

Redis is not a traditional database. It is an in-memory data store that operates at sub-millisecond speed. Think of it as a Swiss Army knife for caching, session storage, message queues, rate limiting, and real-time features like leaderboards or pub/sub messaging.

I use Redis alongside my primary database in every project that grows beyond a simple CRUD app. It handles the things that need to be fast: caching expensive database queries, storing user sessions, managing background job queues with Celery or BullMQ, and rate-limiting API endpoints.

Redis is simple to learn. The data structures (strings, hashes, lists, sets, sorted sets) map naturally to common problems. You can have it running locally in minutes and start seeing performance improvements immediately.

Key Differences

These tools solve fundamentally different problems. PostgreSQL is your system of record, the source of truth for all persistent data. Redis is your speed layer, handling the things that need to happen in microseconds. Comparing them head-to-head misses the point because most production systems use both.

Persistence vs. speed. PostgreSQL writes to disk with full ACID guarantees. Your data survives crashes, power failures, and server restarts. Redis stores everything in memory. While it does support persistence (RDB snapshots and AOF logs), it is designed primarily for speed, not durability. If Redis loses data, you regenerate it from your primary database.

Data modeling is completely different. Postgres uses tables, rows, columns, foreign keys, and SQL queries. Redis uses key-value pairs with specialized data structures. You do not query Redis the way you query Postgres. You design your Redis keys around access patterns, not relationships.

Cost at scale. PostgreSQL stores data on disk, so storage is cheap. Redis stores everything in RAM, which is expensive. A 100GB Postgres database costs pennies. A 100GB Redis instance costs serious money. For a solo developer, this matters when your cached data grows.

The license situation. Redis changed its license in 2024, moving away from pure open source. This led to community forks like Valkey. PostgreSQL remains fully open source with no corporate owner. Something to keep in mind for long-term projects.

When to Choose PostgreSQL

• You need a primary database for your application
• You want ACID-compliant, durable data storage
• You need complex queries, joins, and aggregations
• You are building a CRUD application with relational data
• You want one database that handles structured and semi-structured data

When to Choose Redis

• You need caching to speed up slow database queries
• You want fast session storage for authenticated users
• You need a message queue for background jobs (Celery, Sidekiq, BullMQ)
• You are building real-time features like leaderboards or pub/sub
• You need rate limiting on API endpoints

The Verdict

This is not an either/or decision. PostgreSQL is your primary database. Redis is your performance layer. For a solo developer starting out, begin with just PostgreSQL. It handles everything for small to medium applications without any additional complexity.

When your app grows and you need caching, background jobs, or real-time features, add Redis. The combination of Postgres plus Redis is one of the most battle-tested architectures in production software. I run this exact pair on every project I build, and it handles everything I throw at it. Start with Postgres, add Redis when you feel the pain, and you will have a stack that scales with you.