A Pythonic Approach to Scaling PostgreSQL From Monolith to Shards

PostgreSQL sharding is a horizontal scaling technique that splits data across multiple database servers to handle massive growth. The guide covers when to consider sharding, how to choose effective shard keys like tenant_id, and provides practical Python implementation examples using SQLAlchemy. It demonstrates building a custom session manager for routing queries to correct shards and introduces Citus as a production-ready extension that abstracts sharding complexity while maintaining standard SQL interfaces.