When to Use NoSQL vs SQL¶
SQL is not outdated. NoSQL is not better. It depends on the use case.
SQL (Relational)¶
- ACID transactions
- Structured data with relationships
- Powerful query language (SQL)
- Data integrity
- Horizontal scaling is more complex
- Schema migrations required
Examples: PostgreSQL, MySQL, MariaDB.
Document (MongoDB, CouchDB)¶
- Flexible schema
- Horizontal scaling
- Good for nested data
- No JOINs (data duplication)
- Eventual consistency
Key-Value (Redis, DynamoDB)¶
- Ultra fast (sub-ms)
- Simple API
- Great for cache, sessions, rate limiting
- Limited query capabilities
When to Use What¶
- E-commerce, finance, CRM -> SQL
- Content management, catalogs -> Document
- Cache, sessions, leaderboards -> Key-Value
- Time series -> TimescaleDB, InfluxDB
- Search -> Elasticsearch
- Graphs -> Neo4j
Default Choice¶
PostgreSQL. Handles relational data, JSON (jsonb), full-text search, time series (TimescaleDB extension). If you are unsure, start with PostgreSQL.
Rule¶
Start with PostgreSQL. Add specialized databases when you have a specific need that PostgreSQL cannot handle efficiently.
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