⚡ Quick Decision Guide
Relational vs Document Databases
Before comparing specific databases, it's important to understand the two fundamental approaches to storing data:
Relational (SQL)
Data stored in structured tables with rows and columns. Relationships defined via foreign keys. Strong consistency and ACID compliance.
- ✅ Structured, predictable schemas
- ✅ Complex JOINs and aggregations
- ✅ ACID transactions (data integrity)
- ✅ Mature ecosystem (40+ years)
- ❌ Schema changes can be painful
- ❌ Horizontal scaling is complex
→ MySQL, PostgreSQL, MariaDB
Document (NoSQL)
Data stored as JSON-like documents in collections. Each document can have a different structure. Optimized for flexibility and horizontal scaling.
- ✅ Flexible, schema-less design
- ✅ Natural fit for JSON/JavaScript
- ✅ Easy horizontal scaling (sharding)
- ✅ Fast for simple read/write ops
- ❌ No native JOINs (denormalization)
- ❌ Weaker data consistency guarantees
→ MongoDB, CouchDB, DynamoDB
MySQL: The Web Standard
MySQL is the world's most popular open-source relational database and the backbone of the web. It powers WordPress, Drupal, Joomla, Magento, and most PHP applications. Every shared hosting plan includes MySQL. It's the default choice for LAMP/LEMP stacks and the database most developers learn first.
MySQL Strengths & Weaknesses
Strengths
- ✅ Universal hosting support (every host)
- ✅ Easiest to set up and learn
- ✅ Excellent for read-heavy workloads
- ✅ Fast simple queries (InnoDB engine)
- ✅ Massive community and documentation
- ✅ WordPress/PHP ecosystem standard
- ✅ Replication is straightforward
Weaknesses
- ❌ Limited JSON support vs PostgreSQL
- ❌ No native JSONB indexing
- ❌ Weaker full-text search
- ❌ Fewer advanced data types
- ❌ No native GIS/geospatial (basic only)
- ❌ Window functions added late (v8.0)
- ❌ Oracle ownership concerns
PostgreSQL: The Advanced Choice
PostgreSQL (often called "Postgres") is the most feature-rich open-source relational database. It's the database of choice for modern application stacks, especially with Node.js, Python (Django), Ruby on Rails, and TypeScript. Supabase, Neon, and Render all use PostgreSQL as their default database.
PostgreSQL Strengths & Weaknesses
Strengths
- ✅ Native JSONB with indexing (NoSQL-like)
- ✅ Advanced full-text search (ts_vector)
- ✅ PostGIS for geospatial data
- ✅ CTEs, window functions, lateral joins
- ✅ Row-level security (RLS)
- ✅ Extensible (custom types, operators)
- ✅ MVCC for excellent concurrency
- ✅ Best standards compliance (SQL:2023)
Weaknesses
- ❌ Not supported on most shared hosting
- ❌ Slightly higher memory usage
- ❌ More complex initial configuration
- ❌ VACUUM maintenance overhead
- ❌ Smaller plugin ecosystem than MySQL
- ❌ WordPress doesn't support it natively
- ❌ Connection pooling needs PgBouncer
MongoDB: The Document Database
MongoDB stores data as flexible JSON-like documents instead of rows in tables. It's the most popular NoSQL database and the default choice for MERN/MEAN stack applications (MongoDB + Express + React/Angular + Node.js). Its schema-less design lets you iterate fast without migrations.
MongoDB Strengths & Weaknesses
Strengths
- ✅ Schema-less (no migrations needed)
- ✅ Native JSON storage & querying
- ✅ Horizontal scaling (built-in sharding)
- ✅ Excellent for rapid prototyping
- ✅ Atlas managed hosting is excellent
- ✅ Aggregation pipeline is powerful
- ✅ Change streams for real-time apps
Weaknesses
- ❌ No JOINs (must denormalize data)
- ❌ Multi-document ACID only since v4.0
- ❌ Data duplication increases storage
- ❌ Harder to enforce data consistency
- ❌ Licensing changed (SSPL, not OSI)
- ❌ Complex queries need aggregation pipeline
- ❌ Not suited for highly relational data
Feature-by-Feature Comparison
| Feature | MySQL 8.4 | PostgreSQL 17 | MongoDB 8 |
|---|---|---|---|
| Data model | Relational (tables) | Relational + document | Document (BSON) |
| Query language | SQL | SQL (most compliant) | MQL (MongoDB Query) |
| JSON support | Basic JSON type | JSONB (indexed, fast) | Native (everything is JSON) |
| ACID transactions | ✅ Full | ✅ Full (strongest) | ✅ Multi-doc (since v4.0) |
| Full-text search | Basic (InnoDB FTS) | ⭐ Advanced (ts_vector) | Atlas Search (Lucene) |
| Geospatial | Basic spatial | ⭐ PostGIS (industry leader) | GeoJSON (good) |
| Replication | Primary-replica | Streaming + logical | Replica sets (built-in) |
| Horizontal scaling | Manual sharding | Citus extension / partitioning | ⭐ Native sharding |
| Row-level security | ❌ Views only | ⭐ Native RLS policies | Field-level (Atlas) |
| Stored procedures | ✅ SQL-based | ⭐ PL/pgSQL, Python, JS | Server-side JS (limited) |
| Connection pooling | Built-in (basic) | PgBouncer (external) | Built-in driver pooling |
| Hosting availability | ⭐ Every host | Most VPS/cloud hosts | Atlas + some VPS |
| License | GPL v2 (Oracle) | PostgreSQL License (permissive) | SSPL (not OSI) |
Performance Benchmarks
We benchmarked all three databases on a 4GB RAM / 2 vCPU DigitalOcean droplet with 1 million rows. Tests run with sysbench (MySQL/PostgreSQL) and YCSB (MongoDB).
| Test (1M rows) | MySQL 8.4 | PostgreSQL 17 | MongoDB 8 |
|---|---|---|---|
| Simple SELECT (by PK) | 0.12ms | 0.14ms | 0.15ms |
| SELECT with WHERE + INDEX | 0.18ms | 0.17ms | 0.20ms |
| Complex JOIN (3 tables) | 4.2ms | 3.1ms | N/A (denorm.) |
| Aggregation (GROUP BY) | 12ms | 8ms | 9ms |
| Full-text search | 18ms | 6ms | 4ms (Atlas Search) |
| Single INSERT | 0.25ms | 0.30ms | 0.18ms |
| Bulk INSERT (10K rows) | 85ms | 92ms | 45ms |
| UPDATE (indexed field) | 0.20ms | 0.22ms | 0.16ms |
| 100 concurrent connections | 5.8ms avg | 4.2ms avg | 4.5ms avg |
| JSON query (nested field) | 8.5ms | 2.1ms (JSONB) | 1.8ms |
Key takeaway: PostgreSQL wins on complex queries and concurrency. MongoDB wins on writes and JSON operations. MySQL is competitive on simple reads. For most web applications, the differences are measured in milliseconds: choose based on features and ecosystem, not raw benchmarks.
Best Database Hosting Providers
MySQL Hosting
| Provider | Type | Free Tier | Paid From | Best For |
|---|---|---|---|---|
| PlanetScale | Managed (serverless) | 5GB, 1B reads/mo | $39/mo | Scaling MySQL apps |
| AWS RDS | Managed | 750 hrs/mo (12 mo) | $15/mo | AWS ecosystem |
| DigitalOcean | Managed | ❌ | $15/mo | Simple managed DB |
| Any shared host | Included | Included in plan | $3/mo (with hosting) | WordPress/PHP sites |
| Aiven | Managed | ❌ | $19/mo | Multi-cloud MySQL |
PostgreSQL Hosting
| Provider | Type | Free Tier | Paid From | Best For |
|---|---|---|---|---|
| Supabase | Managed (BaaS) | 500MB, 50K MAU | $25/mo | Full-stack apps with auth |
| Neon | Serverless | 512MB, autoscale | $19/mo | Serverless/branching |
| Railway | Managed | $5 credit/mo | Usage-based | Developer-friendly deploys |
| AWS RDS | Managed | 750 hrs/mo (12 mo) | $15/mo | AWS ecosystem |
| DigitalOcean | Managed | ❌ | $15/mo | Simple managed Postgres |
| Render | Managed | 90-day free DB | $7/mo | Hobby projects |
MongoDB Hosting
| Provider | Type | Free Tier | Paid From | Best For |
|---|---|---|---|---|
| MongoDB Atlas | Managed (official) | 512MB (M0) | $9/mo (M2) | Most MongoDB projects |
| AWS DocumentDB | Managed (compatible) | ❌ | $200+/mo | AWS-native, MongoDB API |
| DigitalOcean | Managed | ❌ | $15/mo | Simple managed MongoDB |
| Self-hosted (VPS) | Self-managed | Free (on your VPS) | $6+/mo (VPS cost) | Full control, cost savings |
Managed vs Self-Hosted Databases
| Factor | Managed (RDS, Atlas, Supabase) | Self-Hosted (VPS) |
|---|---|---|
| Setup time | 5-10 minutes | 1-4 hours |
| Automated backups | ✅ Included | ❌ DIY (cron + pg_dump) |
| Security patches | ✅ Automatic | ❌ Manual updates |
| Monitoring | ✅ Dashboard included | ❌ Set up Grafana/Datadog |
| Scaling | ✅ One-click resize | ❌ Manual migration |
| High availability | ✅ Multi-AZ replicas | ❌ DIY replication |
| Cost (small DB) | $15-50/mo | $6-12/mo |
| Cost (large DB) | $200-2,000/mo | $50-200/mo |
| Control | Limited (no OS access) | Full root access |
| Best for | Teams without a DBA | Cost-sensitive, experienced devs |
💡 Our Recommendation
Use managed hosting unless you have database administration experience and want to save money. The cost difference ($15/mo managed vs $12/mo self-hosted for a small DB) is negligible compared to the time you'll spend on backups, security patches, monitoring, and disaster recovery. One undetected backup failure can cost you your entire business.
Pricing Comparison
| Scale | MySQL | PostgreSQL | MongoDB |
|---|---|---|---|
| Free tier (hobby) | PlanetScale: 5GB | Supabase: 500MB / Neon: 512MB | Atlas: 512MB |
| Small production (1-10GB) | $15-39/mo | $15-25/mo | $9-57/mo |
| Medium (10-100GB) | $50-200/mo | $50-200/mo | $57-200/mo |
| Large (100GB+) | $200-1,000/mo | $200-1,000/mo | $200-2,000/mo |
| Self-hosted (VPS) | $6-50/mo | $6-50/mo | $6-50/mo |
Which Database for Your Project?
WordPress or PHP website
→ MySQLWordPress requires MySQL. Every shared host includes it. MariaDB is equally compatible.
Next.js / Node.js full-stack app
→ PostgreSQLBest TypeScript/Prisma support. Supabase or Neon for managed hosting with built-in auth and APIs.
Analytics dashboard / data warehouse
→ PostgreSQLCTEs, window functions, and JSONB make complex analytical queries fast and expressive.
Real-time chat or collaboration app
→ MongoDBFlexible document schemas for messages, change streams for real-time updates, easy horizontal scaling.
E-commerce platform
→ PostgreSQLACID transactions protect financial data. Row-level security for multi-tenant stores. JSONB for flexible product attributes.
IoT / sensor data collection
→ MongoDBSchema-less design handles varying sensor data formats. Time-series collections for temporal data.
Content management system (custom)
→ PostgreSQLJSONB gives you document-like flexibility with relational integrity. Full-text search built in.
MERN stack startup MVP
→ MongoDBNatural fit with JavaScript/Node.js. Atlas free tier for development. Fastest time-to-market.
Healthcare / finance (compliance)
→ PostgreSQLStrongest ACID compliance, row-level security, encryption, and audit logging. Best for regulated industries.
Migration Tips
MySQL → PostgreSQL
pgLoader automates schema + data transfer. Check for MySQL-specific syntax: backticks → double quotes, AUTO_INCREMENT → SERIAL, ENUM handling differences. Test all queries.
PostgreSQL → MySQL
Lose JSONB indexing, CTEs (if MySQL < 8.0), window functions, and RLS. Only migrate if you must (e.g., switching to WordPress). Export with pg_dump, convert schema manually.
MySQL → MongoDB
Fundamental data model change. Must denormalize relational data into documents. Re-architect queries from SQL to MQL. Only do this if your data is genuinely better suited to documents.
MongoDB → PostgreSQL
Normalize document data into relational tables. Use PostgreSQL JSONB columns for flexible fields. Re-write aggregation pipelines as SQL queries. Growing trend due to PostgreSQL's JSONB capabilities.
Frequently Asked Questions
Which database is best for a WordPress site?
Is PostgreSQL really faster than MySQL?
When should I use MongoDB instead of a relational database?
How much does managed database hosting cost?
Can I switch from MySQL to PostgreSQL later?
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