Choosing the Right Database

Every database decision starts with the shape of your data. Structured data with relationships → relational (PostgreSQL). Flexible, evolving schemas → document (MongoDB, Firestore). High-speed key lookups and caching → key-value (Redis, DynamoDB). Analytics over millions of rows → columnar (BigQuery, Redshift). Semantic search and AI retrieval → vector (pgvector, Pinecone). Relationship traversal → graph (Neo4j, Neptune). Time-series metrics → InfluxDB, TimescaleDB. Most applications use more than one. A common production stack: PostgreSQL as the system of record, Redis as the cache and session store, and pgvector or Pinecone for semantic search. Start with the simplest option that fits your data shape. Add a second database only when the first one demonstrably cannot handle the use case — not because it looks impressive on a diagram.