Memilih database yang tepat adalah keputusan system-design yang kunci — antara SQL (relasional) dan tipe NoSQL (dokumen, key-value, dll.), berdasarkan data, pola akses, skala, dan kebutuhan konsistensi. Database yang berbeda sesuai dengan kebutuhan yang berbeda.
SQL vs NoSQL (pilihan utama)
SQL (relational: PostgreSQL, MySQL) → structured data, tables, relationships, ACID:
✓ strong consistency, complex queries/joins, transactions, well-defined schema
✓ for: relational data, transactions, complex queries (most traditional apps)
NOSQL → various non-relational models, flexible schema, often easier horizontal scaling:
→ DOCUMENT (MongoDB) → flexible JSON-like docs
→ KEY-VALUE (Redis, DynamoDB) → simple, fast lookups, caching
→ WIDE-COLUMN (Cassandra) → massive scale, high write throughput
→ GRAPH (Neo4j) → relationships/networks
✓ for: flexible schema, huge scale, specific access patterns, high throughput
