Database Selection

Database Selection

When to use

• Choosing primary database for a new service
• Adding a specialized database (cache, search, analytics, time-series)
• Evaluating polyglot persistence or multi-database architecture

Core principles

1. PostgreSQL is the default — handles 10k TPS, JSONB, full-text search, extensions
2. Add databases for specific access patterns — not because it's trendy
3. Every additional database doubles operational complexity — worth it only for clear ROI
4. Consistency model is a product decision — strong vs eventual affects user experience
5. Benchmark with YOUR data — vendor benchmarks are meaningless for your workload

References available

• references/​relational-comparison.md — Postgres vs MySQL vs SQLite vs CockroachDB
• references/​nosql-comparison.md — MongoDB vs DynamoDB vs Cassandra vs Redis use cases
• references/​specialized-databases.md — TimescaleDB, Neo4j, Pinecone, pgvector, Elasticsearch
• references/​multi-database-patterns.md — polyglot persistence, CQRS stores, data sync

Scripts available

• scripts/​analyze-data-model.sh — reads schema/​migration files to suggest database fit

Assets available

• assets/​database-decision-matrix.md — fillable template: requirements → recommendation