MySQL vs Redis for Solo Developers

Quick Comparison

MySQL Overview

MySQL is the relational database that powers most of the web. It stores data in tables with defined schemas, enforces relationships with foreign keys, and handles everything from simple CRUD operations to complex queries with joins and aggregations. Every web framework, every hosting provider, and every tutorial supports MySQL.

For a solo developer, MySQL is the dependable workhorse. It writes your data to disk, guarantees ACID compliance, handles concurrent users, and keeps your information safe through crashes and restarts. Whether you are building a blog, an e-commerce store, or a SaaS application, MySQL holds your persistent data reliably.

Redis Overview

Redis is an in-memory data store built for speed. It operates at sub-millisecond latency because everything lives in RAM. Redis supports specialized data structures: strings, hashes, lists, sets, sorted sets, streams, and more. Each structure maps naturally to common application problems.

You use Redis for caching database queries (turn a 200ms query into a 1ms cache hit), storing user sessions (fast authentication checks), managing job queues (background processing with Sidekiq, BullMQ, or Celery), rate limiting APIs, and powering real-time features like leaderboards and pub/sub messaging.

Redis is not typically your primary database. It is the performance layer that sits alongside your primary database and handles the things that need to be blazing fast.

Key Differences

These solve fundamentally different problems. MySQL is your system of record. It stores users, orders, content, and everything that needs to persist reliably. Redis is your speed layer. It caches expensive queries, manages sessions, and handles ephemeral data that needs to be fast. Most production applications use both together.

Data durability is the core tradeoff. MySQL writes to disk with full ACID guarantees. If your server loses power, your data is safe. Redis stores everything in memory. While it supports persistence (RDB snapshots and AOF logging), it is designed for speed first and durability second. If Redis loses data, you regenerate it from MySQL.

Query capabilities are in different universes. MySQL supports SQL with joins, subqueries, aggregations, GROUP BY, window functions, and complex WHERE clauses. Redis has no query language in the traditional sense. You access data by key or use data-structure-specific commands. Need to find all users in a city who signed up last month? MySQL handles this natively. Redis does not.

Memory vs. disk economics. MySQL stores data on disk. A million rows of user data might use a few gigabytes of disk space, which costs pennies. Redis stores everything in RAM. The same data in Redis costs significantly more because RAM is expensive. For a solo developer, this means Redis is for hot data (frequently accessed, small-ish) and MySQL is for everything.

Setup complexity differs by use case. MySQL is a standalone database. You install it, create tables, and start querying. Redis alongside MySQL means running two data stores, managing two connections, implementing cache invalidation logic, and handling the consistency between them. This added complexity is worth it for performance-critical applications but unnecessary for simple ones.

When to Choose MySQL

• You need a primary database for persistent data storage
• You want relational data modeling with joins and foreign keys
• You are building a standard web application (CRUD, user management, content)
• You need complex queries and reporting
• You are using PHP/Laravel or WordPress

When to Choose Redis

• You need sub-millisecond caching for slow database queries
• You want fast session storage for authenticated users
• You need a job queue for background processing
• You are building real-time features (leaderboards, live counters, pub/sub)
• You need rate limiting on API endpoints

The Verdict

MySQL and Redis are partners, not competitors. Start with MySQL as your primary database. It handles all your persistent data reliably and efficiently. When your application grows and you need caching, background jobs, or real-time features, add Redis as a complement.

For a solo developer just starting out, MySQL alone is perfectly fine. Adding Redis too early introduces complexity (cache invalidation, two data stores to manage) without meaningful benefit. But when you feel the pain of slow queries, need background job processing, or want real-time features, Redis is the tool that solves those problems elegantly. The most common production architecture in the world is a relational database plus Redis, and for good reason.