data-ontologistlisted

# Polyglot Persistence Architecture Architectural guidance for using multiple database technologies together, with emphasis on PostgreSQL/Supabase (relational), Neo4j (graph), and MongoDB (document). Demonstrates when to use each database type and how to integrate them effectively. ## When This Skill Applies Use this skill when: - Designing data architecture for new projects - Choosing between relational, graph, and document databases - Integrating multiple database types - Schema design decisions - Query optimization across databases - Migration strategies - Questions about when to use which database paradigm ## Core Principle **Start with the graph. Optimise from there.** Most real-world domains are fundamentally about relationships. The graph is the truest representation of how entities connect. Start by thinking in nodes and edges — then decide where to persist based on access patterns and consistency needs. **Right database for right data concern** Don't force all data into one database type. Use: - **Relational (PostgreSQL/Supabase)** - Structured data, transactions, strong consistency - **Graph (Neo4j)** - Relationships as primary concern, traversal queries - **Document (MongoDB)** - Semi-structured data, flexible schemas, nested documents ### Graph-First Modelling Process Before choosing databases, model the domain as a graph: 1. **Identify nodes** — What are the entities? (Users, Courses, Organisations, Products) 2. **Identify edges** — How do they conne