Connection Pooling — Why Your App Runs Out of Connections
Understand database connection limits, how connection pooling works, and how to configure poolers like PgBouncer and Supabase's built-in pooler.
12 min readdatabases, postgres, connection-pooling, pgbouncer, supabase, performance
Your app works perfectly in development. One user, one connection, no problems. You deploy to production and it runs fine with 10 users. Then traffic picks up, and suddenly:
FATAL: too many connections for role "postgres"
FATAL: remaining connection slots are reserved for superuser connectionsYour database is refusing new connections. Your app is down. This is one of the most common production issues, and it's almost always solved by connection pooling.
Why Connections Are Expensive
Every time your application opens a connection to PostgreSQL, the database:
- Forks a new process. Each connection gets its own operating system process (not a thread — a full process).
- Allocates memory. Each connection consumes roughly 5-10 MB of RAM for buffers and state.
This lesson is part of the Guild Member curriculum. Plans start at $29/mo.