Choosing the right database engine affects your application's performance, scalability, and development speed for years to come. This guide compares the four most common database systems you'll encounter on a VPS.
Quick Comparison
| Database | Type | Best For |
|---|---|---|
| MySQL / MariaDB | Relational (SQL) | WordPress, general web apps, WHMCS, wide CMS compatibility |
| PostgreSQL | Relational (SQL) | Complex queries, JSON/JSONB data, apps needing strict standards compliance |
| MongoDB | NoSQL (document) | Flexible/evolving schemas, APIs, content with varied structure |
| Redis | In-memory key-value | Caching, sessions, queues — not a primary data store |
MySQL / MariaDB
The default choice for most CMS platforms (WordPress, Joomla, Drupal) and PHP frameworks. Extremely well-documented, widely hosted, and simple to operate for typical web application workloads.
PostgreSQL
Preferred when your application needs advanced SQL features, strict data integrity, complex joins/aggregations, or native JSON querying. Popular with Django, Ruby on Rails, and modern SaaS backends.
MongoDB
A good fit when your data doesn't map cleanly to fixed tables — e.g. documents with varying fields, rapid prototyping, or content aggregated from multiple inconsistent sources. Trade-off: less mature support for complex multi-table relationships compared to SQL databases.
Redis
Not a replacement for any of the above — it's an in-memory layer used alongside a primary database for caching, session storage, rate limiting, and message queues. Data is typically ephemeral or secondary, not your source of truth.
Decision Guide
- Building a WordPress site or standard CMS? — MySQL/MariaDB
- Building a SaaS app with complex relational data and reporting? — PostgreSQL
- Building an API with flexible/evolving data structures? — MongoDB
- Need to speed up an existing app or handle sessions/queues? — Add Redis alongside your primary database
Can You Combine Them?
Yes — a very common production pattern is PostgreSQL or MySQL as the primary data store, with Redis layered on top for caching and session management. See How to Run MySQL, PostgreSQL & Redis in Docker Containers for a practical setup.
Resource Considerations on a VPS
| Database | Typical Minimum RAM |
|---|---|
| MySQL/MariaDB (small app) | 1–2 GB |
| PostgreSQL (small app) | 1–2 GB |
| MongoDB | 2 GB+ |
| Redis (cache-only use) | 256 MB–1 GB |
FAQ
Is it hard to switch databases later?
Migrating between SQL databases (MySQL to PostgreSQL) requires schema and query adjustments; migrating from SQL to NoSQL (or vice versa) is more involved and usually requires application-level changes — choosing carefully upfront saves significant rework.
Can I run more than one database engine on the same VPS?
Yes, provided the VPS has sufficient RAM/CPU for all of them running simultaneously.
Continue Reading
- How to Install and Secure MySQL 8 on Ubuntu & Debian
- How to Install PostgreSQL on Ubuntu & Debian
- How to Install MongoDB on Ubuntu & Debian
- How to Install and Secure Redis on Ubuntu & Debian
Browse more articles in Databases.
