PostgreSQL Primary–Replica Demo with FastAPI

Goal

Simple read/write splitting using PostgreSQL streaming replication.

Features:

• PostgreSQL primary + read-replica via Docker Compose
• DB initialization via docker-entrypoint-initdb.d
• FastAPI app with routing:
  • writes → primary
  • reads → replica

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1. Start the DB Cluster

make pg-up

2. DB initialization

All .sql files inside the init/ directory run automatically on first startup.

3. Run the app

make run-app