Advanced Database Architecture — Connection Pooling, PgBouncer, and Transaction Isolation Levels
BACKEND SERIES Day 31: Advanced Database Architecture — Connection Pooling, PgBouncer, and Transaction Isolation Levels 15 min read Series: Logic & Legacy Day 31 / 50 Level: Senior / Database Reliability ⏳ Context: High-concurrency async Python services (like FastAPI or async SQLAlchemy) can easily spawn thousands of concurrent green threads or asyncio tasks. But PostgreSQL uses a process-per-connection model. Spawning 5,000 direct database connections causes memory exhaustion, severe context switching overhead, and connection starvation ( FATAL: sorry, too many clients already ). Today, we dive deep into database scaling architecture: Connection Pooling, PgBouncer multiplexing, and ACID Transaction Isolation Levels. 1. The PostgreSQL Process-Per-Connection Cost Unlike MySQL (which uses threads), PostgreSQL forks a dedicated OS process ( postgres: user db [idle] ) for every active client connection. Each connection consumes approximately 2MB to 10MB of R...
